Phenotypic spectrum and responses to recombinant human IGF1 (rhIGF1) therapy in patients with homozygous intronic pseudoexon growth hormone receptor mutation

in European Journal of Endocrinology
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  • 1 Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine & Dentistry, Queen Mary University of London, London, UK
  • | 2 Birmingham Heartlands Hospital, Heart of England NHS Foundation Trust, Birmingham, UK
  • | 3 The Leeds Teaching Hospital NHS Trust, Leeds, UK
  • | 4 Royal Manchester Children’s Hospital, Central Manchester University Hospitals NHS Foundation Trust, Manchester, UK
  • | 5 Maimonides Pediatric Specialty Center, Brooklyn, New York, USA
  • | 6 CHOC Children’s Clinic, Orange, California, USA
  • | 7 Royal Stoke University Hospital, Stoke-on-Trent, UK
  • | 8 Birmingham Children’s Hospital, Birmingham, UK
  • | 9 Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, UK

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Background

Patients with homozygous intronic pseudoexon GH receptor (GHR) mutations (6Ψ) have growth hormone insensitivity (GHI) (growth failure, IGF1 deficiency and normal/elevated serum GH). We report 9 patients in addition to previously described 11 GHR 6Ψ patients and their responses to rhIGF1 therapy.

Methods

20 patients (12 males, 11 families, mean age 4.0 ± 2.2 years) were diagnosed genetically in our centre. Phenotypic data and responses to rhIGF1 treatment were provided by referring clinicians. Continuous parametric variables were compared using Student t-test or ANOVA.

Results

10/20 (50%) had typical facial features of GHI, 19/20 (95%) from consanguineous families and 18/20 (90%) of Pakistani origin. At diagnosis, mean height SDS: −4.1 ± 0.95, IGF1 SDS: −2.8 ± 1.4; IGFBP3 SDS: −3.0 ± 2.1 and mean basal and peak GH levels: 11.9 µg/L and 32.9 µg/L, respectively. 1/12 who had IGF1 generation test, responded (IGF1: 132–255 ng/mL). 15/20 (75%; 11M) received rhIGF1 (mean dose: 114 µg/kg twice daily, mean duration: 5.3 ± 2.5 years). Mean baseline height velocity of 4.7 ± 1.1 cm/year increased to 7.4 ± 1.8 cm/year (P = 0.001) during year 1 of therapy. Year 3 mean height SDS (−3.2 ± 1.0) was higher than pre-treatment height SDS (−4.3 ± 0.8) (P = 0.03). Mean cumulative increase in height SDS after year 5 was 1.4 ± 0.9. Difference between target height (TH) SDS and adult or latest height SDS was less than that of TH SDS and pre-treatment height SDS (2.1 ± 1.2 vs 3.0 ± 0.8; P = 0.02).

Conclusion

In addition to phenotypic heterogeneity in the cohort, there was mismatch between clinical and biochemical features in individual patients with 6Ψ GHR mutations. rhIGF1 treatment improved height outcomes.

Abstract

Background

Patients with homozygous intronic pseudoexon GH receptor (GHR) mutations (6Ψ) have growth hormone insensitivity (GHI) (growth failure, IGF1 deficiency and normal/elevated serum GH). We report 9 patients in addition to previously described 11 GHR 6Ψ patients and their responses to rhIGF1 therapy.

Methods

20 patients (12 males, 11 families, mean age 4.0 ± 2.2 years) were diagnosed genetically in our centre. Phenotypic data and responses to rhIGF1 treatment were provided by referring clinicians. Continuous parametric variables were compared using Student t-test or ANOVA.

Results

10/20 (50%) had typical facial features of GHI, 19/20 (95%) from consanguineous families and 18/20 (90%) of Pakistani origin. At diagnosis, mean height SDS: −4.1 ± 0.95, IGF1 SDS: −2.8 ± 1.4; IGFBP3 SDS: −3.0 ± 2.1 and mean basal and peak GH levels: 11.9 µg/L and 32.9 µg/L, respectively. 1/12 who had IGF1 generation test, responded (IGF1: 132–255 ng/mL). 15/20 (75%; 11M) received rhIGF1 (mean dose: 114 µg/kg twice daily, mean duration: 5.3 ± 2.5 years). Mean baseline height velocity of 4.7 ± 1.1 cm/year increased to 7.4 ± 1.8 cm/year (P = 0.001) during year 1 of therapy. Year 3 mean height SDS (−3.2 ± 1.0) was higher than pre-treatment height SDS (−4.3 ± 0.8) (P = 0.03). Mean cumulative increase in height SDS after year 5 was 1.4 ± 0.9. Difference between target height (TH) SDS and adult or latest height SDS was less than that of TH SDS and pre-treatment height SDS (2.1 ± 1.2 vs 3.0 ± 0.8; P = 0.02).

Conclusion

In addition to phenotypic heterogeneity in the cohort, there was mismatch between clinical and biochemical features in individual patients with 6Ψ GHR mutations. rhIGF1 treatment improved height outcomes.

Introduction

Growth hormone insensitivity (GHI) is characterised by growth failure, IGF1 deficiency and normal or elevated serum GH. A continuum of genetic, phenotypic and biochemical abnormalities has been established, associated with defects in linear growth (1). Monogenic defects in the GH-IGF1 axis leading to GHI have been discovered in GHR (2, 3), STAT5B (4, 5), IGFALS (6), PAPPA2 (7) and IGF1 (8) genes.

Within the growth hormone receptor (GHR) gene, more than 70 missense, nonsense and splice mutations in over 250 patients have been described (1). The majority of GHR defects are homozygous or compound heterozygous mutations in the region encoding the GHR extracellular domain, responsible for GH binding (9, 10). GHR mutations cause a continuum of phenotypes ranging from severe, with classical GHI facies and undetectable IGF1 levels (11, 12), to mild with no dysmorphic features. The latter is commonly associated with heterozygous dominant negative (13, 14) or compound heterozygous GHR mutations (15).

The intronic GHR pseudoexon mutation (6Ψ) was first described in 2001 in four siblings with mild GHI from a highly consanguineous Pakistani family. This point mutation (base change A−1 to G−1) in intron 6 leads to aberrant splicing and activation of a pseudoexon sequence causing a spectrum of clinical and biochemical abnormalities (16). The inclusion of an additional 108 bases between exons 6 and 7 of the GHR gene translates to the insertion of 36 new amino acids within the extracellular domain and impaired function of the mutant GHR protein (17). In 2007, a further seven 6Ψ patients were reported (18) with more severe GHI phenotypes and heights as low as −6.0 SDS.

We have identified nine further 6Ψ subjects and report the clinical and biochemical features in the cohort of twenty patients. Additionally, we describe growth responses to rhIGF1 therapy, which has not previously been reported.

Subjects and methods

Patients

Between 2001 and 2014, 20 patients (11 families, 10 with parental consanguinity) were diagnosed with the intronic GHR 6Ψ mutation in our centre. There were 12 males and 8 females, mean age at presentation was 4.0 ± 2.2 years (range 0.7–13.0 years). The patients were investigated in 5 UK and 1 US paediatric endocrinology centres.

Clinical, auxological and biochemical data

The patients were investigated at their home institutions and the referring physicians completed a proforma detailing the clinical and biochemical details at the time of sending the DNA sample for genetic analysis. Height measurements were obtained using a wall-mounted stadiometer. Pubertal staging was done using Tanner stages (19, 20). Pre-pubertal patients were Tanner stage 1 genital development or breast development for boys and girls, respectively. Pubertal patients were Tanner stage 2 or above genital or breast development for boys or girls, respectively.

Birth weight, parental height, height and BMI values were expressed as SDS according to the appropriate UK-WHO growth national standards (21, 22, 23). Biochemical investigations included: basal and/or peak GH, basal IGF1 and peak IGF1 during an IGF1 generation test (IGFGT) and basal IGFBP-3 levels. Basal GH levels and GH provocation tests (glucagon, clonidine or arginine stimulation tests or insulin tolerance tests) were performed in the local centres. IGF1 and IGFBP3 values were expressed as SDS based on the age and sex appropriate ranges provided by the host institution. Where serum IGF1 was undetectable (less than the lower limit of the assay) (n = 7), the lowest detectable SDS was calculated for statistical analysis. IGFGTs were performed locally as previously published (dose of GH 0.033 mg/kg body weight daily for 4 days) (24, 25). An increase in IGF1 level of >15 ng/mL between basal and peak values in the IGFGT was considered a positive response (24).

Therapy with rhIGF1

Patients were treated with recombinant human IGF1 (rhIGF1) at their local centres by the referring paediatric endocrinologists. Auxology data (height and weight) at different time points of treatment and the relevant clinical data (e.g. pubertal stage, concomitant treatment, etc.) were provided by the referring clinicians. Auxology data were excluded from statistical analysis if the patient had greater than 6 months interruption of rhIGF1 treatment.

Genetic analysis

Genomic DNA was isolated from peripheral blood leukocytes (Qiagen DNeasy Kit). Each exon of the GHR, plus the pseudoexon (6Ψ), including their intronic boundaries, were amplified by PCR using specific primers (primer sequences available on request). PCR products were visualized on 1% agarose gel and sent subsequently for Sanger sequencing. Sanger sequencing was performed by the Barts and the London Genome Centre (http://www.smd.qmul.ac.uk/gc/) or GATC Biotech (https://www.gatc-biotech.com).

Ethical approval

Informed written consent for genetic research and publication of their clinical details and clinical images were obtained from patients and/or their parents. The study was approved by the Health Research Authority, East of England – Cambridge East Research Ethics Committee (REC reference: 17/EE/0178).

Statistical analysis

For responses to rhIGF1 therapy, the primary end point was height velocity (HV) at the end of the first year of treatment. Pearson correlation coefficient assessed the following correlations: height SDS and IGF1 SDS, height SDS and IGFBP-3 SDS, first year HV and age at initiation of treatment, sex of patient, baseline height SDS and baseline IGF1 SDS.

Pre-treatment HV/height SDS and HV/height SDS during years 1, 2 and 3 of rhIGF1 treatment were compared with ANOVA with Bonferroni correction for multiple comparisons. The difference between TH SDS and pre-treatment height SDS was compared to the difference between TH SDS and adult height/height at latest assessment by unpaired two-tailed Student’s t-test. A P value of ≤0.05 was considered significant.

Results

Phenotypic details

Clinical and biochemical details are shown in Table 1. The mean height SDS of the subjects was −4.1 ± 0.95 (range: −1.7 to −5.9); mean IGF1 SDS was −2.8 ± 1.4 (range: −1.0 to −6.8); mean IGFBP-3 SDS was −3.0 ± 2.1 (range: −0.6 to −8.9); mean basal GH level was 11.9 µg/L (range: 0.1–19.3) and mean peak GH level was 32.9 µg/L (range: 10.0 to >40). Ten out of 20 (50%) patients had classical facial features of GHI (defined as mid-facial hypoplasia, depressed nasal bridge and prominent forehead (26)); 19/20 (95%) were from consanguineous families and 18/20 (90%) are of Pakistani origin. Consistent with the previous results, wide ranges of short stature and biochemical abnormalities are noted.

Table 1

Clinical and auxological details of the patients with homozygous GHR pseudoexon (6Ψ) mutations.

FamilyPatientAge (years)SexHeight SDSBMI SDSBirth weight SDSTarget height SDSEthnicity/consanguinityGHI classical facial features
A1*1.3M−1.7−4.9−0.2−2.2Pak/+No
2*3.7M−5.9−2.00.3−2.2Pak/+No
3*8.3M−3.3−0.4NK−1.6Pak/+No
4*3.8M−3.6−0.5−0.1−1.6Pak/+No
5*1.2F−4.4+1.80.7−2.4Pak/+No
62.5F−4.4−0.1−1.8NKPak/+Yes
B1*1.6F−5.6−2.4−1.4−1.4Pak/+Yes
C1*NKM−5.0NKNKNKPalestine-Arab/+Yes
D1*3.3M−4.90.1NKNKPak/+No
2*8.1M−3.3−2.4−1.5NKPak/+No
E1*5.4F−3.50.02NKNKPak/+No
2*NKF−4.0NKNKNKPak/+No
F17.0M−4.2−0.5−0.5−0.9Pak/+No
G12.6M−3.8−2.9−2.9−1.3Pak/+Yes
23.7F−4.2−0.90.10.7Pak/+Yes
H15.7M−3.0−0.70.7−0.7Pak/+Yes
21.5F−4.7−1.2NK−0.7Pak/+Yes
I12.3F−4.3−1.7−1.7−1.6Ind/−Yes
J15.3F−4.00.40.1−1.6Pak/+Yes
K14.3F−4.1−0.2−0.3−0.9Pak/+Yes

Age and height SDS are at presentation; GHI facial features: frontal bossing, mid-facial hypoplasia.

*Patients previously reported (16, 18).

+, parents consanguineous; −, parents not consanguineous; Ind, Indian; NK, not known; Pak, Pakistani.

Variable phenotypic and biochemical features between and within kindreds

Patient A6 is related to the previously described highly consanguineous Pakistani family (A1–A5) (16, 18). Unlike the other family members, she had facial features of GHI with mid-facial hypoplasia, depressed nasal bridge and prominent forehead. Patients A2 and A5, from the same family, had similar or more severe degrees of short stature (height SDS: −5.4 and −4.4, respectively) but, lacked abnormal facial features. Patient B had a moderate clinical phenotype, height: −5.6 SDS but IGF1 SDS was only slightly subnormal (−2.3 SDS). Families G and H (2 pairs of siblings) showed more phenotypic variability with moderate short stature (height SDS: −3.4 to −4.7), relatively mild biochemical features (IGF1 SDS: −2.3 to −3.1) and variable peak GH (18 to >33 μg/L) but all had classical facial GHI features. Similarly, patients I and K had mild-to-moderate phenotypes and abnormal facial features. In contrast, families D and E (2 pairs of siblings) and patient F had moderate clinical and biochemical features, similar to patients A6, I and K but lacked facial abnormalities. Finally, patient J (distant cousin of A5) had typical GHI facial features and a severe biochemical phenotype but height was moderately low (height: −4.0 SDS).

IGF1 generation test (IGFGT)

Twelve out of 20 subjects underwent IGFGT (Table 2). Only 1 patient (D2) showed a response, with increase of IGF1 from 132 to 255 ng/mL. His height was −4.9 SDS, and he had normal facial features (Fig. 1).

Figure 1
Figure 1

Patient with homozygous GHR pseudoexon mutation and normal facial features. A patient with the homozygous GHR pseudoexon mutation but no dysmorphic facial features i.e. no frontal bossing or mid-facial hypoplasia.

Citation: European Journal of Endocrinology 178, 5; 10.1530/EJE-18-0042

Table 2

Biochemical details of patients with homozygous GHR pseudoexon (6Ψ) mutations.

FamilyPatientBasal GH (μg/L)Peak GH (μg/L)IGF1 SDSIGFGT basal/peak (ng/mL)IGFBP3 SDS
A1*11.010.0−2.523.0/24.0−6.0
2*6.014.3−2.521.0/26.0−8.9
3*1.853.3−1.729.0/36.0−2.9
4*17.590.0−2.020.0/20.0−3.4
5*0.118.8−2.2ND−1.72
63.426.7NKNDND
B1*13.0>33.3−2.36.9/7.6−2.4
C1*0.6NKNKNKNK
D1*10.215.4−2.336.0/41.0−2.6
2*0.328.4−0.7132.0/255.0*−1.6
E1*2.527.0−1.0ND−2.3
2*8.337.7−1.4ND−2.3
F12.040.0−2.541.2/29.7−2.6
G14.0>33.0−2.363.3/16.8ND
216.933.3−2.5NDND
H117.590.0−2.91.5/8.4−2.4
20.118.8−3.1NDND
I13.426.7−2.1NDND
J119.3>40.0−6.8<25.0/<25.0ND
K10.6NK−4.0<22.9/<22.9−2.4

*Positive response during IGFGT.

IGFGT, IGF1 generation test; ND, not done; NK, not known.

Relationships between height and IGF1 and IGFBP-3

There was no positive correlation between height SDS and basal IGF1 SDS or between height SDS and IGFBP-3 SDS.

Responses to rhIGF1 therapy

15 out of 20 patients (75%; 11M) received rhIGF1 treatment. The mean age at initiation of rhIGF1 in all subjects was 9.0 ± 2.7 years (range: 5.7–15.3) and the mean duration of treatment was 5.3 ± 2.5 years (range: 1.5–7.6). The mean dose of rhIGF1 was 114 (range: 110–130) µg/kg twice a day. 5 of 15 patients had received combination rhIGF1/IGFBP-3 therapy as part of a previous study (27). Of these 5 patients, in the first 5 years of treatment, 1 had >6 months interrupted rhIGF1 treatment between years 2 and 3, the rest had uninterrupted rhIGF1 therapy. 10 of 15 patients were treatment naïve. In this group, 5 patients had treatment gaps of >6 months between years 4 and 5 of therapy. Height outcomes were analysed at baseline (n = 15), year 1 (n = 15), year 2 (n = 14) and year 3 (n = 10) (Figs 2 and 3).

Figure 2
Figure 2

Height velocity at four different time points during treatment with rhIGF1. Box and whisker plots show the median, upper and lower quartiles and range; IQR, interquartile range; n, number of patients data available/included for each time point; P values calculated by ANOVA with Dunn–Bonferroni post hoc pairwise comparison; *P = 0.001.

Citation: European Journal of Endocrinology 178, 5; 10.1530/EJE-18-0042

Figure 3
Figure 3

Height SDS at four different time points during treatment with rhIGF1. Box and whisker plots show the median, upper and lower quartiles and range; IQR, interquartile range; n, number of patients data available/included for each time point; P values calculated by ANOVA with Dunn–Bonferroni post hoc pairwise comparison; *P = 0.03.

Citation: European Journal of Endocrinology 178, 5; 10.1530/EJE-18-0042

Mean cumulative height SDS change over 5 years of treatment was calculated in 9 patients (4 previously treated and 5 treatment naïve). 3 of 15 patients were pubertal at the start of rhIGF-I therapy and were concomitantly commenced on GnRH analogue therapy.

Change in HV during years 1, 2 and 3 of rhIGF1 therapy

Baseline mean HV was 4.7 ± 1.1 cm/year and increased to 7.4 ± 1.8 cm/year during the first year of treatment (P = 0.001) (Fig. 2). The first year HV in the treatment-naïve patients (n = 10) was 7.9 ± 1.6 cm/year, which was comparable to HV in the previously treated group (n = 5) (6.3 ± 1.9 cm/year; P = 0.12). There was no significant correlation between year 1 mean HV or year 1 mean HV SDS with sex, age at rhIGF1 initiation, baseline height SDS, baseline BMI SDS or baseline IGF1 SDS.

Mean HV during the years 2 and 3 of rhIGF1 treatment were 5.6 ± 1.8 cm/year and 5.3 ± 1.9 cm/year, respectively. Although these values were above baseline, the difference was not significant (P = 0.11 and 0.36, respectively) (Fig. 2). In treatment-naïve group, there were also no significant differences in mean HV at year 2 and 3 compared to baseline.

Change in height SDS during years 1, 2 and 3 of rhIGF1 therapy

Mean height SDS at year 1 and year 2 of rhIGF1 therapy were −3.8 ± 0.9 and −3.4 ± 1.0, respectively. These values were not significantly different from pre-treatment height SDS (−4.3 ± 0.8, Fig. 3). In the treatment-naïve group, there were also no significant differences in height SDS at year 1 and 2 compared to baseline. Mean height SDS at year 3 of treatment (−3.2 ± 1.0) was, however, significantly higher than pre-treatment height SDS (P = 0.03) (Fig. 3). In the naïve group, mean height SDS also increased significantly from −4.1 ± 0.8 at baseline to −2.9 ± 1.0 at year 3 (P = 0.01). The mean cumulative change in height SDS at year 5 of continuous treatment in 9 treated patients was 1.4 ± 0.9 (range: 0.2–3.2).

Adult height (AH) at discontinuation of rhIGF1 therapy and height at latest assessment (LH) for patients with ongoing rhIGF1 therapy

12 (8M) of 15 treated patients have completed linear growth (AH). 7 of 12 were naive to rhIGF1 therapy and 5 had received rhIGF1/IGFBP-3 therapy previously (27). The mean AH SDS was −3.3 ± 1.3 SDS (−5.7 to −1.8), compared to pre-treatment height SDS (−4.3 ± 0.9 SDS; −5.9 to −3.2) (P = 0.05). Mean AH in the treatment-naïve group (n = 7) was −3.1 ± 1.3 SDS (−5.7 to −1.8), and this was also higher than the pre-treatment mean height SDS −4.1 ± 0.9 SDS (−5.9 to −3.2) (P = 0.08). The individual growth curves for 8 male and 4 female patients are shown in Fig. 4A and B, respectively.

Figure 4
Figure 4

Individual growth curves for homozygous GHR pseudoexon mutation patients who have completed rhIGF-I therapy. (A) Individual growth and adult height data of 8 male patients, compared with the UK-WHO growth standards (21, 22, 23) (upper shaded area; mean represents the 50th centile; +2 s.d. represents the 91st centile; −2 s.d. represents the 2nd centile on the UK-WHO charts) and the mean ± 2 s.d. for height for untreated Laron syndrome patients (lower shaded area; represents reference range for patients with presumed GH receptor abnormalities (28)). (B) Individual growth and adult height data of 4 female patients, compared with the UK-WHO growth standards (21, 22, 23) (upper shaded area; mean represents the 50th centile; +2 s.d. represents the 91st centile; −2 s.d. represents the 2nd centile on the UK-WHO charts) and the mean ± 2 s.d. for height for untreated Laron syndrome patients (lower shaded area; represents reference range for patients with presumed GH receptor abnormalities (28)).

Citation: European Journal of Endocrinology 178, 5; 10.1530/EJE-18-0042

In 3 of 15 patients who remained on rhIGF1 therapy (all naïve to rhIGF1, ages at latest assessment 9.2, 11.0 and 12.3 years), LH was −3.1 ± 0.1 SDS (−3.2 to −3.0), and this was higher than pre-treatment height SDS −4.2 ± 0.6 SDS (−4.8 to −3.6) (P = 0.03).

The difference between target height (TH) SDS and AH/LH SDS was less than that of TH SDS and pre-treatment height SDS (2.1 ± 1.2 vs 3.0 ± 0.8; P = 0.02) (Fig. 5).

Figure 5
Figure 5

Difference between target height (TH) and heights pre- and post-treatment with rhIGF1. Box and whisker plot showing A: Difference between target height (TH) SDS and pre-treatment baseline height SDS and B: Difference between target height SDS and height SDS at final adult height (AH) or at latest assessment (LH) during treatment with rhIGF1 therapy. Box plots show the median, upper and lower quartiles and range; IQR, interquartile range; P values calculated by Student’s unpaired t-test; *P = 0.02.

Citation: European Journal of Endocrinology 178, 5; 10.1530/EJE-18-0042

Heights in the untreated patients

In the 3 untreated patients, AH SDS was −3.5 and −5.0 and LH SDS (at age of 5.0 years) was −4.4 SDS.

Discussion

It is well established that GHR gene mutations cause a continuum of phenotypes, even within families with the same mutation (11, 29, 30). Our cohort of 20 patients with the rare intronic GHR pseudoexon mutation (6Ψ) provides further insights into the phenotypic variation of GHI caused by a single mutation. Consistent with the previous report (18), the spectrum of phenotypic variability is marked. The 6Ψ GHR mutation leads to aberrant splicing, resulting in an aberrant splice product of the GHR gene. This splicing process is highly variable; hence, variable quantities of normal and abnormal transcripts will be generated. Gene transcript heterogeneity i.e. the ratio of abnormal (mutated GHR) to normal (wild-type GHR) proteins and the role of genetic and environmental factors in defining this ratio have been postulated to play a role in the clinical variability (16, 18). However, this needs to be further explored in 6Ψ patients with a range of phenotypes to establish whether patients with more severe phenotypes have relatively more mutant protein transcript.

The characteristic facial features seen in severe GHI, namely, mid-facial hypoplasia and prominent forehead, reflect the underdevelopment of the facial bones secondary to IGF1 deficiency (12, 31). As such, it has been proposed that the degree of craniofacial changes are likely to be more prominent in patients with more severe short stature and/or a greater degree of IGF1 deficiency (31, 32). However, in our cohort, the presence or absence of abnormal facial features did not correlate with either the degree of short stature or the biochemical abnormalities.

Previous studies have shown that serum IGF1 and IGFBP-3 levels correlate with height SDS values in patients with GHR mutations causing severe GHI i.e. the more severe the IGF1 deficiency (IGFD), the more severe the height deficiency (29). The mismatch between clinical phenotype (i.e. degree of short stature) and the biochemical deficiency (IGF1 SDS) in our cohort is striking. IGF1 levels were measured at the 6 referral centres; hence, several different IGF1 assays were used. However, taking this limitation into account, many of the most severely affected patients (height SDS −4.0 to −5.9) have IGF1 SDS values, which are in the normal range or mildly reduced (−2.9 to −1.4). The reason for this discrepancy is unclear but may be a result of additive molecular defects in other proteins downstream from the GHR resulting in a greater degree of short stature e.g. the IGF1 receptor or signalling molecules of RAS-MAP kinase pathway and/or the PI3-K/Akt pathway. Other genetic and/or environmental factors involved in the GHR processing, trafficking and receptor degradation pathways may also be implicated (18). The use of different, rather than standardized/centralized IGF-1 assays, may also contribute to the observed discrepancy.

The majority of reported patients with GHR 6Ψ mutations are of Pakistani origin and previous work by our group suggests the presence of a common ancestor (18). Although most of the families were reportedly unrelated, patients J1 and A5 were distant cousins.

Response to rhIGF1 therapy has not been previously assessed in patients with 6Ψ GHR mutations. Given that a number of patients in our cohort had a mild degree of IGF1 deficiency, it is tempting to speculate that the response to rhIGF1 therapy would be sub-optimal. However, the first year growth response, demonstrated by the significant increase in height velocity (baseline HV: 4.7 ± 1.1 cm/year and year 1 HV: 7.4 ± 1.8 cm/year) in our patients, was comparable to that reported in patients with other homozygous GHR defects (baseline HV: 4.7 ± 1.3 cm/year and year 1 HV: 8.2 ± 0.8 m/year) (33) and other patients with severe IGF1 deficiency (baseline values: 2.8–4.0 cm/year and year 1 HV: 7.4–8.5 cm/year) (34, 35, 36, 37). Contrary to reported data from a large European cohort of patients on rhIGF1 (38), the increase in 1st year HV in our cohort did not correlate with age of rhIGF1 initiation or lower baseline height SDS. Furthermore, similar to other studies (34, 35), the growth-promoting effects of rhIGF1 appeared to persist, as there was a significant improvement in height SDS at year 3 of treatment. The mean change in height SDS in our cohort following 5 years of treatment was 1.4 ± 0.9 and is comparable to another published study of patients with GHI (mean change 1.4 after 6 years of therapy) (36). Similar to other studies (34, 35), our patients who had completed rhIGF1 therapy, did not achieve adult heights in the normal range. However, the AH was higher than the pre-treatment height SDS and indicates a positive effect of rhIGF1 on growth outcome (34). Overall, the effect of rhIGF1 therapy on height outcomes in our cohort was encouraging.

Only one subject, D2, responded during the IGFGT. His height was −4.9 SDS, and he had normal facial features. Although he was treated with rhIGF1 therapy, data on his clinical course and response to treatment were unavailable; hence, he was not included in the 15 treated patients described in this manuscript.

In summary, the homozygous intronic 6Ψ GHR mutation caused both severe and mild GHI phenotypes, even in individuals within the same kindred. The presence or absence of abnormal facial features did not correlate with either the degree of short stature or the biochemical abnormalities. There was often a mismatch between the clinical and biochemical features in individual patients. rhIGF1 treatment improved long-term height outcomes as has been demonstrated in GHI patients with other homozygous GHR mutations and primary IGF1 deficiency.

Declaration of interest

The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of this study.

Funding

The genetic sequencing service was supported by a research grant from Ipsen UK (H L S). S C and L S were supported by William Harvey sponsored Clinical Research Fellowship.

Author contribution statement

S C, S J R, T M, P E C, S B T, A B, U K, R D and H L S contributed to patient recruitment, data collection and analysis. L S and L A M performed the genetic analysis. S C performed phenotypic and statistical analyses. S C wrote the manuscript with input from M O S and H L S.

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    • Search Google Scholar
    • Export Citation
  • 4

    Kofoed EM, Hwa V, Little B, Woods KA, Buckway CK, Tsubaki J, Pratt KL, Bezrodnik L, Jasper H & Tepper A et al. Growth hormone insensitivity associated with a STAT5b mutation. New England Journal of Medicine 2003 349 11391147. (https://doi.org/10.1056/NEJMoa022926)

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 5

    Rosenfeld RG, Belgorosky A, Camacho-Hubner C, Savage MO, Wit JM & Hwa V. Defects in growth hormone receptor signaling. Trends in Endocrinology and Metabolism 2007 18 134141. (https://doi.org/10.1016/j.tem.2007.03.004)

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 6

    Domené HM, Bengolea SV, Martinez AS, Ropelato MG, Pennisi P, Scaglia P, Heinrich JJ & Jasper HG. Deficiency of the circulating insulin-like growth factor system associated with inactivation of the acid-labile subunit gene. New England Journal of Medicine 2004 350 570577. (https://doi.org/10.1056/NEJMoa0131000)

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 7

    Dauber A, Munoz-Calvo MT, Barrios V, Domene HM, Kloverpris S, Serra-Juhe C, Desikan V, Pozo J, Muzumdar R & Martos-Moreno GA et al. Mutations in pregnancy-associated plasma protein A2 cause short stature due to low IGF-I availability. EMBO Molecular Medicine 2016 8 363374. (https://doi.org/10.15252/emmm.201506106)

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 8

    Woods KA, Camacho-Hubner C, Savage MO & Clark AJ. Intrauterine growth retardation and postnatal growth failure associated with deletion of the insulin-like growth factor I gene. New England Journal of Medicine 1996 335 13631367. (https://doi.org/10.1056/NEJM199610313351805)

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 9

    Savage MO, Hwa V, David A, Rosenfeld RG & Metherell LA. Genetic defects in the growth hormone-IGF1 axis causing growth hormone insensitivity and impaired linear growth. Frontiers in Endocrinology 2011 2 112. (https://doi.org/10.3389/fendo.2011.00095)

    • Search Google Scholar
    • Export Citation
  • 10

    Wit JM, van Duyvenvoorde HA, Scheltinga SA, de Bruin S, Hafkenscheid L, Kant SG, Ruivenkamp CA, Gijsbers AC, van Doorn J & Feigerlova E et al. Genetic analysis of short children with apparent growth hormone insensitivity. Hormone Research in Paediatrics 2012 77 320333. (https://doi.org/10.1159/000338462)

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 11

    Rosenfeld RG, Rosenbloom AL & Guevara-Aguirre J. Growth hormone (GH) insensitivity due to primary GH receptor deficiency. Endocrine Reviews 1994 15 369390. (https://doi.org/10.1210/edrv-15-3-369)

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 12

    Savage MO, Attie KM, David A, Metherell LA, Clark AJ & Camacho-Hubner C. Endocrine assessment, molecular characterization and treatment of growth hormone insensitivity disorders. Nature Clinical Practice. Endocrinology and Metabolism 2006 2 395407. (https://doi.org/10.1038/ncpendmebib195)

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 13

    Ayling RM, Ross R, Towner P, Von Laue S, Finidori J, Moutoussamy S, Buchanan CR, Clayton PE & Norman MR. A dominant-negative mutation of the growth hormone receptor causes familial short stature. Nature Genetics 1997 16 1314. (https://doi.org/10.1038/ng0597-13)

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 14

    Iida K, Takahashi Y, Kaji H, Nose O, Okimura Y, Abe H & Chihara K. Growth hormone (GH) insensitivity syndrome with high serum GH-binding protein levels caused by a heterozygous splice site mutation of the GH receptor gene producing a lack of intracellular domain. Journal of Clinical Endocrinology and Metabolism 1998 83 531537. (https://doi.org/10.1210/jcem.83.2.4601)

    • Search Google Scholar
    • Export Citation
  • 15

    Fang P, Riedl S, Amselem S, Pratt KL, Little BM, Haeusler G, Hwa V, Frisch H & Rosenfeld RG. Primary growth hormone (GH) insensitivity and insulin-like growth factor deficiency caused by novel compound heterozygous mutations of the GH receptor gene: genetic and functional studies of simple and compound heterozygous states. Journal of Clinical Endocrinology and Metabolism 2007 92 22232231. (https://doi.org/10.1210/jc.2006-2624)

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 16

    Metherell LA, Akker SA, Munroe PB, Rose SJ, Caulfield M, Savage MO, Chew SL & Clark AJ. Pseudoexon activation as a novel mechanism for disease resulting in a typical growth hormone insensitivity. American Journal of Human Genetics 2001 69 641646. (https://doi.org/10.1086/323266)

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 17

    Maamra M, Milward A, Esfahani HZ, Abbott LP, Metherell LA, Savage MO, Clark AJ & Ross RJ. A 36 residues insertion in the dimerization domain of the growth hormone receptor results in defective trafficking rather than impaired signalling. Journal of Endocrinology 2006 188 251261. (https://doi.org/10.1677/joe.1.06252)

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 18

    David A, Camacho-Hubner C, Bhangoo A, Rose SJ, Miraki-Moud F, Akker SA, Butler GE, Ten S, Clayton PE & Clark AJ et al. An intronic growth hormone receptor mutation causing activation of a pseudoexon is associated with a broad spectrum of growth hormone insensitivity phenotypes. Journal of Clinical Endocrinology and Metabolism 2007 92 655659. (https://doi.org/10.1210/jc.2006-1527)

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 19

    Marshall WA & Tanner JM. Variations in the pattern of pubertal changes in boys. Archives of Disease in Childhood 1970 45 1323. (https://doi.org/10.1136/adc.45.239.13)

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 20

    Marshall WA & Tanner JM. Variations in pattern of pubertal changes in girls. Archives of Disease in Childhood 1969 44 291303. (https://doi.org/10.1136/adc.44.235.291)

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 21

    Freeman JV, Cole TJ, Chinn S, Jones PR, White EM, Preece MA. Cross sectional stature and weight reference curves for the UK, 1990. Archives of Disease in Childhood 1995 73 1724. (https://doi.org/10.1136/adc.73.1.17)

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 22

    WHO Multicentre Growth Reference Study Group. WHO child growth standards based on length/height, weight and age. Acta Paediatrica Supplement 2006 450 7685.

    • Search Google Scholar
    • Export Citation
  • 23

    WHO. WHO Child Growth Standards: Methods and Development. Geneva: WHO, 2006.

  • 24

    Blum WF, Cotterill AM, Postel-Vinay MC, Ranke MB, Savage MO, Wilton P. Improvement of diagnostic criteria in growth hormone insensitivity syndrome: solutions and pitfalls. Pharmacia Study Group on Insulin-like Growth Factor I Treatment in Growth Hormone Insensitivity Syndromes. Acta Paediatrica Supplement 1994 399 117124. (https://doi.org/10.1111/j.1651-2227.1994.tb13303.x)

    • Search Google Scholar
    • Export Citation
  • 25

    Cotterill AM, Camacho-Hubner C, Woods K, Martinelli C, Duquesnoy P, Savage MO. The insulin-like growth factor I generation test in the investigation of short stature. Acta Paediatrica Supplement 1994 399 128130. (https://doi.org/10.1111/j.1651-2227.1994.tb13305.x)

    • Search Google Scholar
    • Export Citation
  • 26

    Laron Zvi. Laron syndrome (primary growth hormone resistance or insensitivity): the Personal Experience 1958–2003. Journal of Clinical Endocrinology and Metabolism 2004 89 10311044. (https://doi.org/10.1210/jc.2003-031033)

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 27

    Camacho-Hübner C, Rose S, Preece M & Savage MO. Pharmacokinetic studies of recombinant human insulin-like growth factor I (rhIGF-I)/rhIGF-binding protein-3 complex administered to patients with growth hormone insensitivity syndrome. Journal of Clinical Endocrinology and Metabolism 2006 91 12461253. (https://doi.org/10.1210/jc.2005-101)

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 28

    Laron Z, Lilos P & Klinger B. Growth curves for Laron syndrome. Archives of Disease in Childhood 1993 68 768770 (https://doi.org/10.1136/adc.68.6.768)

  • 29

    Woods KA, Dastot F, Preece MA, Clark AJ, Postel-Vinay MC, Chatelain PG, Ranke MB, Rosenfeld RG, Amselem S & Savage MO. Phenotype: genotype relationships in growth hormone insensitivity syndrome. Journal of Clinical Endocrinology and Metabolism 1997 82 35293535. (https://doi.org/10.1210/jcem.82.11.4389)

    • Search Google Scholar
    • Export Citation
  • 30

    Rosenbloom AL, Guevara-Aguirre J, Rosenfeld RG & Francke U. Growth hormone receptor deficiency in Ecuador. Journal of Clinical Endocrinology and Metabolism 1999 84 44364443. (https;//doi.org/10.1210/jcem.84.12.6283)

    • Search Google Scholar
    • Export Citation
  • 31

    Kurtoglu S. & Hatipoglu N. Growth Hormone Insensitivity: diagnostic and therapeutic approaches. Journal of Endocrinological Investigation 2016 39 19. (https://doi.org/10.1007/s40618-015-0327-2)

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 32

    Burren CP, Woods KA, Rose SJ, Tauber M, Price DA, Heinrich U, Gilli G, Razzaghy-Azar M, Al-Ashwal A & Crock PA et al. Clinical and endocrine characteristics in atypical and classical growth hormone insensitivity syndrome. Hormone Research 2001 55 125130. (https://doi.org/10.1159/000049983)

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 33

    Klinger B & Laron Z. Three year IGF-I treatment of children with Laron syndrome. Journal of Pediatric Endocrinology and Metabolism 1995 8 149158. (https://doi.org/10.1515/JPEM.1995.8.3.149)

    • Search Google Scholar
    • Export Citation
  • 34

    Backeljauw PF, Kuntze J, Frane J, Calikoglu AS & Chernausek SD. Adult and near-adult height in patients with severe insulin-like growth factor-i deficiency after long-term therapy with recombinant human insulin-like growth factor-I. Hormone Research in Paediatrics 2013 80 4756. (https://doi.org/10.1159/000351958)

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 35

    Chernausek SD, Backeljauw PF, Frane J, Kuntze J & Underwood LE. Long-term treatment with recombinant insulin-like growth factor (IGF)-I in children with severe IGF-I deficiency due to growth hormone insensitivity. Journal of Clinical Endocrinology and Metabolism 2007 92 902910. (https://doi.org/10.1210/jc.2006-1610)

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 36

    Backeljauw PF & Underwood LE. Therapy for 6.5–7.5 years with recombinant insulin-like growth factor I in children with growth hormone insensitivity syndrome: a clinical research center study. Journal of Clinical Endocrinology and Metabolism 2001 86 15041510. (https://doi.org/10.1210/jcem.86.4.7381)

    • Search Google Scholar
    • Export Citation
  • 37

    Ranke MB, Savage MO, Chatelain PG, Preece MA, Rosenfeld RG, Blum WF & Wilton P. Insulin-like growth factor I improves height in growth hormone insensitivity: two years’ results. Hormone Research 1995 44 253264. (https://doi.org/10.1159/000184637)

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 38

    Bang P, Polak M, Woelfle J, Houchard A. Effectiveness and safety of rhIGF1 therapy in children: the European Increlex® Growth Forum Database Experience. Hormone Research in Paediatrics 2015 83 345357. (https://doi.org/10.1159/000371798)

    • Crossref
    • Search Google Scholar
    • Export Citation

 

     European Society of Endocrinology

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  • View in gallery

    Patient with homozygous GHR pseudoexon mutation and normal facial features. A patient with the homozygous GHR pseudoexon mutation but no dysmorphic facial features i.e. no frontal bossing or mid-facial hypoplasia.

  • View in gallery

    Height velocity at four different time points during treatment with rhIGF1. Box and whisker plots show the median, upper and lower quartiles and range; IQR, interquartile range; n, number of patients data available/included for each time point; P values calculated by ANOVA with Dunn–Bonferroni post hoc pairwise comparison; *P = 0.001.

  • View in gallery

    Height SDS at four different time points during treatment with rhIGF1. Box and whisker plots show the median, upper and lower quartiles and range; IQR, interquartile range; n, number of patients data available/included for each time point; P values calculated by ANOVA with Dunn–Bonferroni post hoc pairwise comparison; *P = 0.03.

  • View in gallery

    Individual growth curves for homozygous GHR pseudoexon mutation patients who have completed rhIGF-I therapy. (A) Individual growth and adult height data of 8 male patients, compared with the UK-WHO growth standards (21, 22, 23) (upper shaded area; mean represents the 50th centile; +2 s.d. represents the 91st centile; −2 s.d. represents the 2nd centile on the UK-WHO charts) and the mean ± 2 s.d. for height for untreated Laron syndrome patients (lower shaded area; represents reference range for patients with presumed GH receptor abnormalities (28)). (B) Individual growth and adult height data of 4 female patients, compared with the UK-WHO growth standards (21, 22, 23) (upper shaded area; mean represents the 50th centile; +2 s.d. represents the 91st centile; −2 s.d. represents the 2nd centile on the UK-WHO charts) and the mean ± 2 s.d. for height for untreated Laron syndrome patients (lower shaded area; represents reference range for patients with presumed GH receptor abnormalities (28)).

  • View in gallery

    Difference between target height (TH) and heights pre- and post-treatment with rhIGF1. Box and whisker plot showing A: Difference between target height (TH) SDS and pre-treatment baseline height SDS and B: Difference between target height SDS and height SDS at final adult height (AH) or at latest assessment (LH) during treatment with rhIGF1 therapy. Box plots show the median, upper and lower quartiles and range; IQR, interquartile range; P values calculated by Student’s unpaired t-test; *P = 0.02.

  • 1

    David A, Hwa V, Metherell LA, Netchine I, Camacho-Hubner C, Clark AJ, Rosenfeld RG & Savage MO. Evidence for a continuum of genetic, phenotypic, and biochemical abnormalities in children with growth hormone insensitivity. Endocrine Reviews 2011 32 472497. (https://doi.org/10.1210/er.2010-0023)

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 2

    Godowski PJ, Leung DW, Meacham LR, Galgani JP, Hellmiss R, Keret R, Rotwein PS, Parks JS, Laron Z & Wood WI. Characterization of the human growth hormone receptor gene and demonstration of a partial gene deletion in two patients with Laron-type dwarfism. PNAS 1989 86 80838087. (https://doi.org/10.1073/pnas.86.20.8083)

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 3

    Amselem S, Duquesnoy P, Attree O, Novelli G, Bousnina S, Postel-Vinay MC & Goossens M. Laron dwarfism and mutations of the growth hormone-receptor gene. New England Journal of Medicine 1989 321 989995. (https://doi.org/10.1056/NEJM198910123211501)

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 4

    Kofoed EM, Hwa V, Little B, Woods KA, Buckway CK, Tsubaki J, Pratt KL, Bezrodnik L, Jasper H & Tepper A et al. Growth hormone insensitivity associated with a STAT5b mutation. New England Journal of Medicine 2003 349 11391147. (https://doi.org/10.1056/NEJMoa022926)

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 5

    Rosenfeld RG, Belgorosky A, Camacho-Hubner C, Savage MO, Wit JM & Hwa V. Defects in growth hormone receptor signaling. Trends in Endocrinology and Metabolism 2007 18 134141. (https://doi.org/10.1016/j.tem.2007.03.004)

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 6

    Domené HM, Bengolea SV, Martinez AS, Ropelato MG, Pennisi P, Scaglia P, Heinrich JJ & Jasper HG. Deficiency of the circulating insulin-like growth factor system associated with inactivation of the acid-labile subunit gene. New England Journal of Medicine 2004 350 570577. (https://doi.org/10.1056/NEJMoa0131000)

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 7

    Dauber A, Munoz-Calvo MT, Barrios V, Domene HM, Kloverpris S, Serra-Juhe C, Desikan V, Pozo J, Muzumdar R & Martos-Moreno GA et al. Mutations in pregnancy-associated plasma protein A2 cause short stature due to low IGF-I availability. EMBO Molecular Medicine 2016 8 363374. (https://doi.org/10.15252/emmm.201506106)

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 8

    Woods KA, Camacho-Hubner C, Savage MO & Clark AJ. Intrauterine growth retardation and postnatal growth failure associated with deletion of the insulin-like growth factor I gene. New England Journal of Medicine 1996 335 13631367. (https://doi.org/10.1056/NEJM199610313351805)

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 9

    Savage MO, Hwa V, David A, Rosenfeld RG & Metherell LA. Genetic defects in the growth hormone-IGF1 axis causing growth hormone insensitivity and impaired linear growth. Frontiers in Endocrinology 2011 2 112. (https://doi.org/10.3389/fendo.2011.00095)

    • Search Google Scholar
    • Export Citation
  • 10

    Wit JM, van Duyvenvoorde HA, Scheltinga SA, de Bruin S, Hafkenscheid L, Kant SG, Ruivenkamp CA, Gijsbers AC, van Doorn J & Feigerlova E et al. Genetic analysis of short children with apparent growth hormone insensitivity. Hormone Research in Paediatrics 2012 77 320333. (https://doi.org/10.1159/000338462)

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 11

    Rosenfeld RG, Rosenbloom AL & Guevara-Aguirre J. Growth hormone (GH) insensitivity due to primary GH receptor deficiency. Endocrine Reviews 1994 15 369390. (https://doi.org/10.1210/edrv-15-3-369)

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 12

    Savage MO, Attie KM, David A, Metherell LA, Clark AJ & Camacho-Hubner C. Endocrine assessment, molecular characterization and treatment of growth hormone insensitivity disorders. Nature Clinical Practice. Endocrinology and Metabolism 2006 2 395407. (https://doi.org/10.1038/ncpendmebib195)

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 13

    Ayling RM, Ross R, Towner P, Von Laue S, Finidori J, Moutoussamy S, Buchanan CR, Clayton PE & Norman MR. A dominant-negative mutation of the growth hormone receptor causes familial short stature. Nature Genetics 1997 16 1314. (https://doi.org/10.1038/ng0597-13)

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 14

    Iida K, Takahashi Y, Kaji H, Nose O, Okimura Y, Abe H & Chihara K. Growth hormone (GH) insensitivity syndrome with high serum GH-binding protein levels caused by a heterozygous splice site mutation of the GH receptor gene producing a lack of intracellular domain. Journal of Clinical Endocrinology and Metabolism 1998 83 531537. (https://doi.org/10.1210/jcem.83.2.4601)

    • Search Google Scholar
    • Export Citation
  • 15

    Fang P, Riedl S, Amselem S, Pratt KL, Little BM, Haeusler G, Hwa V, Frisch H & Rosenfeld RG. Primary growth hormone (GH) insensitivity and insulin-like growth factor deficiency caused by novel compound heterozygous mutations of the GH receptor gene: genetic and functional studies of simple and compound heterozygous states. Journal of Clinical Endocrinology and Metabolism 2007 92 22232231. (https://doi.org/10.1210/jc.2006-2624)

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 16

    Metherell LA, Akker SA, Munroe PB, Rose SJ, Caulfield M, Savage MO, Chew SL & Clark AJ. Pseudoexon activation as a novel mechanism for disease resulting in a typical growth hormone insensitivity. American Journal of Human Genetics 2001 69 641646. (https://doi.org/10.1086/323266)

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 17

    Maamra M, Milward A, Esfahani HZ, Abbott LP, Metherell LA, Savage MO, Clark AJ & Ross RJ. A 36 residues insertion in the dimerization domain of the growth hormone receptor results in defective trafficking rather than impaired signalling. Journal of Endocrinology 2006 188 251261. (https://doi.org/10.1677/joe.1.06252)

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 18

    David A, Camacho-Hubner C, Bhangoo A, Rose SJ, Miraki-Moud F, Akker SA, Butler GE, Ten S, Clayton PE & Clark AJ et al. An intronic growth hormone receptor mutation causing activation of a pseudoexon is associated with a broad spectrum of growth hormone insensitivity phenotypes. Journal of Clinical Endocrinology and Metabolism 2007 92 655659. (https://doi.org/10.1210/jc.2006-1527)

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 19

    Marshall WA & Tanner JM. Variations in the pattern of pubertal changes in boys. Archives of Disease in Childhood 1970 45 1323. (https://doi.org/10.1136/adc.45.239.13)

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 20

    Marshall WA & Tanner JM. Variations in pattern of pubertal changes in girls. Archives of Disease in Childhood 1969 44 291303. (https://doi.org/10.1136/adc.44.235.291)

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 21

    Freeman JV, Cole TJ, Chinn S, Jones PR, White EM, Preece MA. Cross sectional stature and weight reference curves for the UK, 1990. Archives of Disease in Childhood 1995 73 1724. (https://doi.org/10.1136/adc.73.1.17)

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 22

    WHO Multicentre Growth Reference Study Group. WHO child growth standards based on length/height, weight and age. Acta Paediatrica Supplement 2006 450 7685.

    • Search Google Scholar
    • Export Citation
  • 23

    WHO. WHO Child Growth Standards: Methods and Development. Geneva: WHO, 2006.

  • 24

    Blum WF, Cotterill AM, Postel-Vinay MC, Ranke MB, Savage MO, Wilton P. Improvement of diagnostic criteria in growth hormone insensitivity syndrome: solutions and pitfalls. Pharmacia Study Group on Insulin-like Growth Factor I Treatment in Growth Hormone Insensitivity Syndromes. Acta Paediatrica Supplement 1994 399 117124. (https://doi.org/10.1111/j.1651-2227.1994.tb13303.x)

    • Search Google Scholar
    • Export Citation
  • 25

    Cotterill AM, Camacho-Hubner C, Woods K, Martinelli C, Duquesnoy P, Savage MO. The insulin-like growth factor I generation test in the investigation of short stature. Acta Paediatrica Supplement 1994 399 128130. (https://doi.org/10.1111/j.1651-2227.1994.tb13305.x)

    • Search Google Scholar
    • Export Citation
  • 26

    Laron Zvi. Laron syndrome (primary growth hormone resistance or insensitivity): the Personal Experience 1958–2003. Journal of Clinical Endocrinology and Metabolism 2004 89 10311044. (https://doi.org/10.1210/jc.2003-031033)

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 27

    Camacho-Hübner C, Rose S, Preece M & Savage MO. Pharmacokinetic studies of recombinant human insulin-like growth factor I (rhIGF-I)/rhIGF-binding protein-3 complex administered to patients with growth hormone insensitivity syndrome. Journal of Clinical Endocrinology and Metabolism 2006 91 12461253. (https://doi.org/10.1210/jc.2005-101)

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 28

    Laron Z, Lilos P & Klinger B. Growth curves for Laron syndrome. Archives of Disease in Childhood 1993 68 768770 (https://doi.org/10.1136/adc.68.6.768)

  • 29

    Woods KA, Dastot F, Preece MA, Clark AJ, Postel-Vinay MC, Chatelain PG, Ranke MB, Rosenfeld RG, Amselem S & Savage MO. Phenotype: genotype relationships in growth hormone insensitivity syndrome. Journal of Clinical Endocrinology and Metabolism 1997 82 35293535. (https://doi.org/10.1210/jcem.82.11.4389)

    • Search Google Scholar
    • Export Citation
  • 30

    Rosenbloom AL, Guevara-Aguirre J, Rosenfeld RG & Francke U. Growth hormone receptor deficiency in Ecuador. Journal of Clinical Endocrinology and Metabolism 1999 84 44364443. (https;//doi.org/10.1210/jcem.84.12.6283)

    • Search Google Scholar
    • Export Citation
  • 31

    Kurtoglu S. & Hatipoglu N. Growth Hormone Insensitivity: diagnostic and therapeutic approaches. Journal of Endocrinological Investigation 2016 39 19. (https://doi.org/10.1007/s40618-015-0327-2)

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 32

    Burren CP, Woods KA, Rose SJ, Tauber M, Price DA, Heinrich U, Gilli G, Razzaghy-Azar M, Al-Ashwal A & Crock PA et al. Clinical and endocrine characteristics in atypical and classical growth hormone insensitivity syndrome. Hormone Research 2001 55 125130. (https://doi.org/10.1159/000049983)

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 33

    Klinger B & Laron Z. Three year IGF-I treatment of children with Laron syndrome. Journal of Pediatric Endocrinology and Metabolism 1995 8 149158. (https://doi.org/10.1515/JPEM.1995.8.3.149)

    • Search Google Scholar
    • Export Citation
  • 34

    Backeljauw PF, Kuntze J, Frane J, Calikoglu AS & Chernausek SD. Adult and near-adult height in patients with severe insulin-like growth factor-i deficiency after long-term therapy with recombinant human insulin-like growth factor-I. Hormone Research in Paediatrics 2013 80 4756. (https://doi.org/10.1159/000351958)

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 35

    Chernausek SD, Backeljauw PF, Frane J, Kuntze J & Underwood LE. Long-term treatment with recombinant insulin-like growth factor (IGF)-I in children with severe IGF-I deficiency due to growth hormone insensitivity. Journal of Clinical Endocrinology and Metabolism 2007 92 902910. (https://doi.org/10.1210/jc.2006-1610)

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 36

    Backeljauw PF & Underwood LE. Therapy for 6.5–7.5 years with recombinant insulin-like growth factor I in children with growth hormone insensitivity syndrome: a clinical research center study. Journal of Clinical Endocrinology and Metabolism 2001 86 15041510. (https://doi.org/10.1210/jcem.86.4.7381)

    • Search Google Scholar
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  • 37

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