High Population Frequency of GNRHR p.Q106R in Malta: An Evaluation of Fertility and Hormone Profiles in Heterozygotes

Context

The gonadotropin-releasing hormone receptor variant GNRHR p.Q106R (rs104893836) in homozygosity, compound heterozygosity, or single heterozygosity is often reported as the causative variant in idiopathic hypogonadotropic hypogonadism (IHH) patients with GnRH deficiency. Genotyping of a Maltese newborn cord-blood collection yielded a minor allele frequency (MAF) 10 times higher (MAF = 0.029; n = 493) than that of the global population (MAF = 0.003).

Objective

To determine whether GNRHR p.Q106R in heterozygosity influences profiles of endogenous hormones belonging to the hypothalamic-pituitary axis and the onset of puberty and fertility in adult men (n = 739) and women (n = 239).

Design Setting and Participants

Analysis of questionnaire data relating to puberty and fertility, genotyping of the GNRHR p.Q106R variant, and hormone profiling of a highly phenotyped Maltese adult cohort from the Maltese Acute Myocardial Infarction Study.

Main Outcome and Results

Out of 978 adults, 43 GNRHR p.Q106R heterozygotes (26 men and 17 women) were identified. Hormone levels and fertility for all heterozygotes are within normal parameters except for TSH, which was lower in men 50 years or older.

Conclusion

Hormone data and baseline fertility characteristics of GNRHR p.Q106R heterozygotes are comparable to those of homozygous wild-type individuals who have no reproductive problems. The heterozygous genotype alone does not impair the levels of investigated gonadotropins and sex steroid hormones or affect fertility. GNRHR p.Q106R heterozygotes who exhibit IHH characteristics must have at least another variant, probably in a different IHH gene, that drives pathogenicity. We also conclude that GNRHR p.Q106R is likely a founder variant due to its overrepresentation and prevalence in the island population of Malta.

Genetic architecture of self-limited delayed puberty and congenital hypogonadotropic hypogonadism

Distinguishing between self limited delayed puberty (SLDP) and congenital hypogonadotropic hypogonadism (CHH) may be tricky as they share clinical and biochemical characteristics. and appear to lie within the same clinical spectrum. However, one is classically transient (SDLP) while the second is typically a lifetime condition (CHH). The natural history and long-term outcomes of these two conditions differ significantly and thus command distinctive approaches and management. Because the first presentation of SDLP and CHH is very similar (delayed puberty with low LH and FSH and low sex hormones), the scientific community is scrambling to identify diagnostic tests that can allow a correct differential diagnosis among these two conditions, without having to rely on the presence or absence of phenotypic red flags for CHH that clinicians anyway seem to find hard to process. Despite the heterogeneity of genetic defects so far reported in DP, genetic analysis through next-generation sequencing technology (NGS) had the potential to contribute to the differential diagnostic process between SLDP and CHH. In this review we will provide an up-to-date overview of the genetic architecture of these two conditions and debate the benefits and the bias of performing genetic analysis seeking to effectively differentiate between these two conditions.

New and Consolidated Therapeutic Options for Pubertal Induction in Hypogonadism: In-depth Review of the Literature

Delayed puberty (DP) defines a retardation of onset/progression of sexual maturation beyond the expected age from either a lack/delay of the hypothalamo-pituitary-gonadal axis activation or a gonadal failure. DP usually gives rise to concern and uncertainty in patients and their families, potentially affecting their immediate psychosocial well-being and also creating longer term psychosexual sequelae. The most frequent form of DP in younger teenagers is self-limiting and may not need any intervention. Conversely, DP from hypogonadism requires prompt and specific treatment that we summarize in this review. Hormone therapy primarily targets genital maturation, development of secondary sexual characteristics, and the achievement of target height in line with genetic potential, but other key standards of care include body composition and bone mass. Finally, pubertal induction should promote psychosexual development and mitigate both short- and long-term impairments comprising low self-esteem, social withdrawal, depression, and psychosexual difficulties. Different therapeutic options for pubertal induction have been described for both males and females, but we lack the necessary larger randomized trials to define the best approaches for both sexes. We provide an in-depth and updated literature review regarding therapeutic options for inducing puberty in males and females, particularly focusing on recent therapeutic refinements that better encompass the heterogeneity of this population, and underlining key differences in therapeutic timing and goals. We also highlight persistent shortcomings in clinical practice, wherein strategies directed at "the child with delayed puberty of uncertain etiology" risk being misapplied to older adolescents likely to have permanent hypogonadism.

Predictors of reproductive and non-reproductive outcomes of gonadotropin mediated pubertal induction in male patients with congenital hypogonadotropic hypogonadism (CHH)

PURPOSE

To investigate predictors of testicular response and non-reproductive outcomes (height, body proportions) after gonadotropin-induced puberty in congenital hypogonadotropic hypogonadism (CHH).

DESIGN

A retrospective analysis of the puberty induction in CHH male patients, undergoing an off-label administration of combined gonadotropin (FSH and hCG).

METHODS

Clinical and hormonal evaluations before and during gonadotropin stimulation in 19 CHH patients genotyped by Targeted Next Generation Sequencing for CHH genes; 16 patients underwent also semen analysis after gonadotropins.

RESULTS

A lesser increase in testicular volume after 24 months of induction was significantly associated with: (I) cryptorchidism; (II) a positive genetic background; (III) a complete form of CHH. We found no significant correlation with the cumulative dose of hCG administered in 24 months. We found no association with the results of semen analyses, probably due to the low numerosity. Measures of body disproportion (eunuchoid habitus and difference between adult and target height: deltaSDSth), were significantly related to the: (I) age at the beginning of puberty induction; (II) duration of growth during the induction; (III) initial bone age. The duration of growth during induction was associated with previous testosterone priming and to partial forms of CHH.

CONCLUSIONS

This study shows that a strong genetic background and cryptorchidism, as indicators of a complete GnRH deficiency since intrauterine life, are negative predictors of testicular response to gonadotropin stimulation in CHH. Body disproportion is associated with a delay in treatment and duration of growth during the induction, which is apparently inversely related to previous androgenization.

Increased Burden of Rare Sequence Variants in GnRH-Associated Genes in Women With Hypothalamic Amenorrhea

CONTEXT

Functional hypothalamic amenorrhea (HA) is a common, acquired form of hypogonadotropic hypogonadism that occurs in the setting of energy deficits and/or stress. Variability in individual susceptibility to these stressors, HA heritability, and previous identification of several rare sequence variants (RSVs) in genes associated with the rare disorder, isolated hypogonadotropic hypogonadism (IHH), in individuals with HA suggest a possible genetic contribution to HA susceptibility.

OBJECTIVE

We sought to determine whether the burden of RSVs in IHH-related genes is greater in women with HA than controls.

DESIGN

We compared patients with HA to control women.

SETTING

The study was conducted at secondary referral centers.

PATIENTS AND OTHER PARTICIPANTS

Women with HA (n = 106) and control women (ClinSeq study; n = 468).

INTERVENTIONS

We performed exome sequencing in all patients and controls.

MAIN OUTCOME MEASURE(S)

The frequency of RSVs in 53 IHH-associated genes was determined using rare variant burden and association tests.

RESULTS

RSVs were overrepresented in women with HA compared with controls (P = .007). Seventy-eight heterozygous RSVs in 33 genes were identified in 58 women with HA (36.8% of alleles) compared to 255 RSVs in 41 genes among 200 control women (27.2%).

CONCLUSIONS

Women with HA are enriched for RSVs in genes that cause IHH, suggesting that variation in genes associated with gonadotropin-releasing hormone neuronal ontogeny and function may be a major determinant of individual susceptibility to developing HA in the face of diet, exercise, and/or stress.

Semaphorin Signaling in GnRH Neurons: From Development to Disease

In mammals, fertility critically depends on the pulsatile secretion of gonadotropin-releasing hormone (GnRH) by scattered hypothalamic neurons (GnRH neurons). During development, GnRH neurons originate in the nasal placode and migrate first into the nasal compartment and then through the nasal/forebrain junction, before they reach their final position in the hypothalamus. This neurodevelopmental process, which has been extensively studied in mouse models, is regulated by a plethora of factors that might control GnRH neuron migration or survival as well as the fasciculation/targeting of the olfactory/vomeronasal axons along which the GnRH neurons migrate. Defects in GnRH neuron development or release can lead to isolated GnRH deficiency, with the underlying genetic causes still being partially unknown. Recently, semaphorins and their receptors neuropilins and plexins, a large family of molecules implicated in neuronal development and plasticity, are emerging as key regulators of GnRH neuron biology and deficiency. Specifically, semaphorins have been shown to play different roles in GnRH neuron biology by regulating migration and survival during embryonic development as well as secretion in adulthood.

Gonadotropin-releasing hormone (GnRH) deficiency under treatment: psychological and sexual functioning impacts

OBJECTIVE

GnRH (gonadotropin releasing hormone) is a crucial hormone for sexual development, puberty, and fertility, and its deficiency leads to hypogonadotropic hypogonadism (HH), which causes abnormal secondary sexual development and infertility. The combination of the lack of sense of smell, i.e., anosmia, and HH is a type of GnRH deficiency known as Kallmann syndrome, which affects both men and women. The impact of Kallmann syndrome can be very severe and causes a variety of psychological problems in patients. The aim of the present study was to investigate psychopathology, sexuality, and personality characteristics in patients with GnRH deficiency under hormonal replacement therapy.

DESIGN

A total of 38 patients with GnRH deficiency aged 30.6 ± 10.44 years and 38 healthy matched for age individuals participated in the study and completed a series of questionnaires concerning sexual functioning, ego defense mechanisms, quality of life, personality characteristics, as well as anxiety and depression.

RESULTS

After adjustment for anxiety and depression, no difference in sexuality parameters were reported between men with and without GnRH deficiency, while women with GnRH deficiency had significantly lower sexual desire compared to controls. Concerning quality of life, satisfaction with general health was significantly lower in patients compared to controls, even after adjusting for sex. Furthermore, patients with GnRH deficiency indicated markedly less anxiety and a trend for less depression compared to controls. Finally, defense styles, ego-strength, and hostility did not differ between GnRH deficiency patients and controls.

CONCLUSIONS

Our study is the first to investigate psychological and sexual functioning impacts in patients with GnRH deficiency under hormonal replacement therapy. However, larger studies are needed so as to add further empirical evidence.

Targeted next generation sequencing approach identifies eighteen new candidate genes in normosmic hypogonadotropic hypogonadism and Kallmann syndrome

The genetic basis is unknown for ∼60% of normosmic hypogonadotropic hypogonadism (nHH)/Kallmann syndrome (KS). DNAs from (17 male and 31 female) nHH/KS patients were analyzed by targeted next generation sequencing (NGS) of 261 genes involved in hypothalamic, pituitary, and/or olfactory pathways, or suggested by chromosome rearrangements. Selected variants were subjected to Sanger DNA sequencing, the gold standard. The frequency of Sanger-confirmed variants was determined using the ExAC database. Variants were classified as likely pathogenic (frameshift, nonsense, and splice site) or predicted pathogenic (nonsynonymous missense). Two novel FGFR1 mutations were identified, as were 18 new candidate genes including: AMN1, CCKBR, CRY1, CXCR4, FGF13, GAP43, GLI3, JAG1, NOS1, MASTL, NOTCH1, NRP2, PALM2, PDE3A, PLEKHA5, RD3, and TRAPPC9, and TSPAN11. Digenic and trigenic variants were found in 8/48 (16.7%) and 1/48 (2.1%) patients, respectively. NGS with confirmation by Sanger sequencing resulted in the identification of new causative FGFR1 gene mutations and suggested 18 new candidate genes in nHH/KS.

Gonadotrophin replacement for induction of fertility in hypogonadal men

Congenital hypogonadotrophic hypogonadism (CHH) is a rare form of infertility caused by deficient secretion or action of gonadotrophin-releasing hormone. There is no consensus regarding the optimal approach to fertility treatment in CHH men. In most cases, appropriate hormonal treatment with human chorionic gonadotrophin with or without follicle stimulating hormone will induce testicular development, spermatogenesis and fertility. Recent studies have examined sequential treatment with FSH pre-treatment to optimize fertility outcomes in severely affected CHH patients. This paper reviews historical and recent literature to summarize the current evidence on therapeutic approaches for CHH men seeking fertility.