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Luigi Maione, Andrew A Dwyer, Bruno Francou, Anne Guiochon-Mantel, Nadine Binart, Jérôme Bouligand and Jacques Young

Congenital hypogonadotropic hypogonadism (CHH) and Kallmann syndrome (KS) are rare, related diseases that prevent normal pubertal development and cause infertility in affected men and women. However, the infertility carries a good prognosis as increasing numbers of patients with CHH/KS are now able to have children through medically assisted procreation. These are genetic diseases that can be transmitted to patients’ offspring. Importantly, patients and their families should be informed of this risk and given genetic counseling. CHH and KS are phenotypically and genetically heterogeneous diseases in which the risk of transmission largely depends on the gene(s) responsible(s). Inheritance may be classically Mendelian yet more complex; oligogenic modes of transmission have also been described. The prevalence of oligogenicity has risen dramatically since the advent of massively parallel next-generation sequencing (NGS) in which tens, hundreds or thousands of genes are sequenced at the same time. NGS is medically and economically more efficient and more rapid than traditional Sanger sequencing and is increasingly being used in medical practice. Thus, it seems plausible that oligogenic forms of CHH/KS will be increasingly identified making genetic counseling even more complex. In this context, the main challenge will be to differentiate true oligogenism from situations when several rare variants that do not have a clear phenotypic effect are identified by chance. This review aims to summarize the genetics of CHH/KS and to discuss the challenges of oligogenic transmission and also its role in incomplete penetrance and variable expressivity in a perspective of genetic counseling.

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Anne-Lise Lecoq, Jérôme Bouligand, Mirella Hage, Laure Cazabat, Sylvie Salenave, Agnès Linglart, Jacques Young, Anne Guiochon-Mantel, Philippe Chanson and Peter Kamenický

Context

Recently, germline and somatic GPR101 p.(E308D) mutation was found in patients with isolated acromegaly. It is not known whether GPR101 point mutations are associated with other histological types of pituitary adenoma.

Objective

We sought germline GPR101 mutations in patients with sporadic pituitary adenomas, and compared the phenotypes of GPR101 mutation carriers and AIP mutation carriers.

Design

An observational cohort study performed between 2007 and 2014 in a single referral center.

Participants

This prospective study involved 766 unselected patients (413 women) with sporadic pituitary adenomas of all histotypes.

Methods

Entire GPR101 and AIP coding sequence were screened for germline mutations.

Results

Twelve patients (1.6%) were found to carry the GPR101 p.(E308D) mutation or rare GPR101 variants. The minor allele frequency of the GPR101 mutation and variants was higher in patients with pituitary adenomas than in unaffected individuals included in the Exome Aggregation Consortium database. Three of the six patients with the GPR101 p.(E308D) mutation had adult-onset acromegaly, two had adrenocorticotropin-secreting adenomas, and one had a nonfunctioning macroadenoma. Six patients carried rare GPR101 variants. Germline AIP mutations or rare AIP variants were identified in 32 patients (4.2%). AIP mutation carriers were younger at diagnosis than GPR101 mutation carriers and non carriers. None of the patients harbored mutations in both the GPR101 and AIP genes.

Conclusion

Germline GPR101 mutations are very rare in patients with sporadic pituitary adenomas of various histotypes. No digenism with AIP was identified. Further studies are required to establish whether and how genetic variation in GPR101 gene contributes to pituitary tumorigenesis.

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Frédéric Brioude, Jérôme Bouligand, Séverine Trabado, Bruno Francou, Sylvie Salenave, Peter Kamenicky, Sylvie Brailly-Tabard, Philippe Chanson, Anne Guiochon-Mantel and Jacques Young

Congenital hypogonadotropic hypogonadism (CHH) results from abnormal gonadotropin secretion, and it is characterized by impaired pubertal development. CHH is caused by defective GNRH release, or by a gonadotrope cell dysfunction in the pituitary. Identification of genetic abnormalities related to CHH has provided major insights into the pathways critical for the development, maturation, and function of the reproductive axis. Mutations in five genes have been found specifically in Kallmann's syndrome, a disorder in which CHH is related to abnormal GNRH neuron ontogenesis and is associated with anosmia or hyposmia.

In combined pituitary hormone deficiency or in complex syndromic CHH in which gonadotropin deficiency is either incidental or only one aspect of a more complex endocrine disorder or a non-endocrine disorder, other mutations affecting GNRH and/or gonadotropin secretion have been reported.

Often, the CHH phenotype is tightly linked to an isolated deficiency of gonadotropin secretion. These patients, who have no associated signs or hormone deficiencies independent of the deficiency in gonadotropin and sex steroids, have isolated CHH. In some familial cases, they are due to genetic alterations affecting GNRH secretion (mutations in GNRH1, GPR54/KISS1R and TAC3 and TACR3) or the GNRH sensitivity of the gonadotropic cells (GNRHR). A minority of patients with Kallmann's syndrome or a syndromic form of CHH may also appear to have isolated CHH, but close clinical, familial, and genetic studies can reorient the diagnosis, which is important for genetic counseling in the context of assisted reproductive medicine.

This review focuses on published cases of isolated CHH, its clinical and endocrine features, genetic causes, and genotype–phenotype relationships.

Free access

Marie-Laure Kottler, Yen-Yin Chou, Olivier Chabre, Nicolas Richard, Camille Polge, Sylvie Brailly-Tabard, Philippe Chanson, Anne Guiochon-Mantel, Ilpo Huhtaniemi and Jacques Young

Context

Mutations of the FSH β gene, causing in women isolated FSH deficiency and hypogonadism, are very rare and only a few have been described.

Objective

To describe the phenotype and response to recombinant human (rh) FSH of a female patient with a novel homozygous loss-of-function mutation of FSH β, and to characterize in vitro the molecular mechanisms responsible for the FSH inactivation.

Patient

A 29-year-old woman with primary amenorrhea and impaired pubertal development associated with isolated FSH deficiency.

Methods and results

Sequencing of the FSH β gene revealed a homozygous 1 bp (G) deletion at codon 79 (c.289delG) of exon 3 which produced a frameshift at codon 79 (A79fs108X) and a premature stop codon at codon 109. The wild-type and mutant FSH β cDNAs inserted into expression vector were cotransfected into Chinese hamster ovary cells with the α -subunit. Wild-type FSH was readily detectable in culture medium, whereas no mutant FSH was detectable by either immunoassay or in vitro bioassay. Mutant FSHβ protein could not be detected in western blot.

In response to a 15-day treatment with rhFSH, sonography revealed multifollicular development in the ovaries. Circulating levels of estradiol and inhibin B were dramatically increased, whereas anti-Mullerian hormone decreased. Serum LH first decreased and then increased, inducing multiovulation associated with supraphysiologic progesterone and inhibin A levels.

Conclusion

A novel FSH β mutation was detected in a hypogonadal woman. rhFSH was effective in ovulation induction in the patient but with signs of ovarian hyperstimulation. The high pretreatment LH levels could contribute to this excessive ovarian response to rhFSH.

Free access

Anne Bachelot, Agnès Rouxel, Nathalie Massin, Jérome Dulon, Carine Courtillot, Christine Matuchansky, Yasmina Badachi, Anne Fortin, Bernard Paniel, Fabrice Lecuru, Marie-Aude Lefrère-Belda, Elisabeth Constancis, Elisabeth Thibault, Géri Meduri, Anne Guiochon-Mantel, Micheline Misrahi, Frédérique Kuttenn, Philippe Touraine and on behalf of the POF-GIS Study Group

Objective

Premature ovarian failure (POF) encompasses a heterogeneous spectrum of conditions, with phenotypic variability among patients. The etiology of POF remains unknown in most cases. We performed a global phenotyping of POF women with the aim of better orienting attempts at an etiological diagnosis.

Design and methods

We performed a mixed retrospective and prospective study of clinical, biological, histological, morphological, and genetic data relating to 357 consecutive POF patients between 1997 and 2008. The study was conducted at a reproductive endocrinology referral center.

Results

Seventy-six percent of the patients presented with normal puberty and secondary amenorrhea. Family history was present in 14% of the patients, clinical and/or biological autoimmunity in 14.3%. Fifty-six women had a fluctuating form of POF. The presence of follicles was suggested at ultrasonography in 50% of the patients, and observed in 29% at histology; the negative predictive value of the presence of follicles at ultrasonography was 77%. Bone mineral density alterations were found in 58% of the women. Eight patients had X chromosomal abnormalities other than Turner's syndrome, eight other patients evidenced FMR1 pre-mutation. Two other patients had autoimmune polyendocrine syndrome type 2 and 1.

Conclusion

A genetic cause of POF was identified in 25 patients, i.e. 7% of the whole cohort. POF etiology remains most often undiscovered. Novel strategies of POF phenotyping are in such content mandatory to improve the rate of POF patients for whom etiology is identified.

Free access

Géraldine Vitellius, Séverine Trabado, Christine Hoeffel, Jérôme Bouligand, Antoine Bennet, Frederic Castinetti, Bénédicte Decoudier, Anne Guiochon-Mantel, Marc Lombes, Brigitte Delemer and investigators of the MUTA-GR Study

Background

Recently discovered mutations of NR3C1 gene, encoding for the GR, in patients with glucocorticoid resistance and bilateral adrenal incidentalomas prompted us to investigate whether GR mutations might be associated with adrenal hyperplasia.

Objective

The multicenter French Clinical Research Program (Muta-GR) was set up to determine the prevalence of GR mutations and polymorphisms in patients harboring bilateral adrenal incidentalomas associated with hypertension and/or biological hypercortisolism without clinical Cushing’s signs.

Results

One hundred patients were included in whom NR3C1 sequencing revealed five original heterozygous GR mutations that impaired GR signaling in vitro. Mutated patients presented with mild glucocorticoid resistance defined as elevated urinary free cortisol (1.7 ± 0.7 vs 0.9 ± 0.8 upper limit of normal range, P = 0.006), incomplete 1 mg dexamethasone suppression test without suppressed 8-AM adrenocorticotrophin levels (30.9 ± 31.2 vs 16.2 ± 17.5 pg/mL) compared to the non-mutated patients. Potassium and aldosterone levels were lower in mutated patients (3.6 ± 0.2 vs 4.1 ± 0.5 mmol/L, P = 0.01, and 17.3 ± 9.9 vs 98.6 ± 115.4 pg/mL, P = 0.0011, respectively) without elevated renin levels, consistent with pseudohypermineralocorticism. Ex vivo characterization of mutated patients’ fibroblasts demonstrated GR haploinsufficiency as revealed by below-normal glucocorticoid induction of FKBP5 gene expression. There was no association between GR polymorphisms and adrenal hyperplasia in this cohort, except an over-representation of BclI polymorphism.

Conclusion

The 5% prevalence of heterozygous NR3C1 mutations discovered in our series is higher than initially thought and encourages GR mutation screening in patients with adrenal incidentalomas to unambiguously differentiate from Cushing’s states and to optimize personalized follow-up.