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JM Wit, HV Balen, GA Kamp and W Oostdijk

Experiments of nature and clinical observations have provided indications that postponing puberty may increase final height in short children. In children with central precocious puberty, a GnRH analog (GnRHa) alone is efficacious in increasing final height, but in other conditions a combination of growth hormone (GH) and GnRHa is needed. In GH-deficient children with early onset of puberty and poor height prediction, the combination of GH and GnRHa increases final height by 1.0-1.3 s.d. In children with idiopathic short stature and persistent short stature after intrauterine growth retardation, the combination also appears to be beneficial. Potential side effects include weight gain, a negative effect on bone mineralization, and psychosocial consequences. More data on long-term safety have to be collected before the combination of GH and GnRHa in children with idiopathic short stature should be considered for clinical use outside clinical trials.

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S H Donze, C R Meijer, S G Kant, G R J Zandwijken, A H van der Hout, R M L van Spaendonk, A M W van den Ouweland, J M Wit, M Losekoot and W Oostdijk

Objective

Short stature caused by point mutations or deletions of the short stature homeobox (SHOX) gene (SHOX haploinsufficiency (SHI)) is a registered indication for GH treatment. Patients with a SHOX enhancer deletion (SED) have a similar phenotype, but their response to GH is unknown. It is uncertain if duplications of SHOX or its enhancer (SDUP) cause short stature. This study aimed to describe the clinical characteristics and growth response to GH treatment in patients with aberrations of SHOX and its enhancers.

Design

In this retrospective multi-center study (2002–March 2014) clinical information was available from 130 patients (72 SHI, 44 SED, and 14 SDUP) of whom 52 patients were treated with GH. We evaluated height, sitting height (SH), arm span, dysmorphic features and indicators of the growth response to GH (delta height SDS, height velocity, and index of responsiveness).

Results

Patients with SEDs showed similar HtSDS to patients with SHI (−2.3 and −2.6, respectively, P=0.2), but they were less disproportionate (SH/height ratio SDS 2.0 vs 3.1 (P<0.01) and extremities/trunk ratio 2.57 vs 2.43 (P=0.03)). The 1st year growth response to GH treatment was significantly greater in prepubertal patients with SEDs than SHI. None of the patients with an SDUP was disproportionate and SDUP cosegregated poorly with short stature; their growth response to GH treatment (n=3) was similar to the other groups.

Conclusions

Patients with SEDs are equally short, but less disproportionate than patients with SHI, and show a greater response to GH.

Free access

D Mul, S Wu, R A de Paus, W Oostdijk, A C Lankester, H A van Duyvenvoorde, C A L Ruivenkamp, M Losekoot, M J D van Tol, F De Luca, E van de Vosse and J M Wit

Objective

The established causes of GH insensitivity include defects of the GH receptor and STAT5B. The latter condition is also characterized by severe immunodeficiency. A recent case with short stature, GH resistance, and immunodeficiency due to an I κ B mutation suggests that the NF-κB pathway may interact with STAT5B signaling.

Design

Here, we present a case of a short child with several congenital anomalies as well as GH insensitivity and mild immunodeficiency associated with a mosaic de novo duplication of chromosome 17q21–25, suggesting that overexpression of one of the duplicated genes may be implicated in GH resistance.

Methods and results

In vitro studies on blood lymphocytes showed disturbed signaling of the CD28 pathway, involving NF-κB and related proteins. Functional studies on cultured skin fibroblasts revealed that NF-κB activation, PI3K activity, and STAT5 phosphorylation in response to GH were suppressed, while the sensitivity to GH in terms of MAPK phosphorylation was increased. An in silico analysis of the duplicated genes showed that M AP3K3 and PRKCA are associated with the NF-κB pathway. Baseline MAP3K3 expression in T-cell blasts (TCBs) was normal, but PRKCA expression in TCBs and fibroblasts was significantly higher than that in control cells.

Conclusions

We conclude that the 17q21–25 duplication is associated with GH insensitivity and disturbed STAT5B, PI3K, and NF-κB signaling, possibly due to PRKCA mRNA overexpression.

Free access

S A van Gool, G A Kamp, R J Odink, S M P F de Muinck Keizer-Schrama, H A Delemarre-van de Waal, W Oostdijk and J M Wit

Objective

To assess the long-term effect of prepubertal high-dose GH treatment on growth in children with idiopathic short stature (ISS).

Design and methods

Forty children with no signs of puberty, age at start 4–8 years (girls) or 4–10 years (boys), height SDS <−2.0 SDS, and birth length >−2.0 SDS, were randomly allocated to receive GH at a dose of 2 mg/m2 per day (equivalent to 75 μg/kg per day at start and 64 μg/kg per day at stop) until the onset of puberty for at least 2 years (preceded by two 3-month periods of treatment with low or intermediate doses of GH separated by two washout periods of 3 months) or no treatment. In 28 cases, adult height (AH) was assessed at a mean (s.d.) age of 20.4 (2.3) years.

Results

GH-treated children (mean treatment period on high-dose GH 2.3 years (range 1.2–5.0 years)) showed an increased mean height SDS at discontinuation of the treatment compared with the controls (−1.3 (0.8) SDS versus −2.6 (0.8) SDS respectively). However, bone maturation was significantly accelerated in the GH-treated group compared with the controls (1.6 (0.4) versus 1.0 (0.2) years per year, respectively), and pubertal onset tended to advance. After an untreated interval of 3–12 years, AH was −2.1 (0.7) and −1.9 (0.6) in the GH-treated and control groups respectively. Age was a positive predictor of adult height gain.

Conclusion

High-dose GH treatment restricted to the prepubertal period in young ISS children augments height gain during treatment, but accelerates bone maturation, resulting in a similar adult height compared with the untreated controls.

Restricted access

S Kos, C M Cobbaert, T M Kuijper, W Oostdijk, S E Hannema, J M Wit, N Biermasz and B E P B Ballieux

Free access

Sarina G Kant, Iveta Cervenkova, Lukas Balek, Lukas Trantirek, Gijs W E Santen, Martine C de Vries, Hermine A van Duyvenvoorde, Michiel J R van der Wielen, Annemieke J M H Verkerk, André G Uitterlinden, Sabine E Hannema, Jan M Wit, Wilma Oostdijk, Pavel Krejci and Monique Losekoot

Objective

Mutations of the fibroblast growth factor receptor 3 (FGFR3) cause various forms of short stature, of which the least severe phenotype is hypochondroplasia, mainly characterized by disproportionate short stature. Testing for an FGFR3 mutation is currently not part of routine diagnostic testing in children with short stature without disproportion.

Design

A three-generation family A with dominantly transmitted proportionate short stature was studied by whole-exome sequencing to identify the causal gene mutation. Functional studies and protein modeling studies were performed to confirm the pathogenicity of the mutation found in FGFR3. We performed Sanger sequencing in a second family B with dominant proportionate short stature and identified a rare variant in FGFR3.

Methods

Exome sequencing and/or Sanger sequencing was performed, followed by functional studies using transfection of the mutant FGFR3 into cultured cells; homology modeling was used to construct a three-dimensional model of the two FGFR3 variants.

Results

A novel p.M528I mutation in FGFR3 was detected in family A, which segregates with short stature and proved to be activating in vitro. In family B, a rare variant (p.F384L) was found in FGFR3, which did not segregate with short stature and showed normal functionality in vitro compared with WT.

Conclusions

Proportionate short stature can be caused by a mutation in F GFR3. Sequencing of this gene can be considered in patients with short stature, especially when there is an autosomal dominant pattern of inheritance. However, functional studies and segregation studies should be performed before concluding that a variant is pathogenic.