A report of two novel NR5A1 mutation families: possible clinical phenotype of psychiatric symptoms of anxiety and/or depression

NR5A1 c.991-1G > C splice-site variant causes familial 46,XY partial gonadal dysgenesis with incomplete penetrance

OBJECTIVE

The study aimed to identify the genetic basis of partial gonadal dysgenesis (PGD) in a non-consanguineous family from Estonia.

PATIENTS

Cousins P (proband) 1 (12 years; 46,XY) and P2 (18 years; 46,XY) presented bilateral cryptorchidism, severe penoscrotal hypospadias, low bitesticular volume and azoospermia in P2. Their distant relative, P3 (30 years; 46,XY), presented bilateral cryptorchidism and cryptozoospermia.

DESIGN

Exome sequencing was targeted to P1-P3 and five unaffected family members.

RESULTS

P1-P2 were identified as heterozygous carriers of NR5A1 c.991-1G > C. NR5A1 encodes the steroidogenic factor-1 essential in gonadal development and specifically expressed in adrenal, spleen, pituitary and testes. Together with a previous PGD case from Belgium (Robevska et al 2018), c.991-1G > C represents the first recurrent NR5A1 splice-site mutation identified in patients. The majority of previous reports on NR5A1 mutation carriers have not included phenotype-genotype data of the family members. Segregation analysis across three generations showed incomplete penetrance (<50%) and phenotypic variability among the carriers of NR5A1 c.991-1G > C. The variant pathogenicity was possibly modulated by rare heterozygous variants inherited from the other parent, OTX2 p.P134R (P1) or PROP1 c.301_302delAG (P2). For P3, the pedigree structure supported a distinct genetic cause. He carries a previously undescribed likely pathogenic variant SOS1 p.Y136H. SOS1, critical in Ras/MAPK signalling and foetal development, is a strong novel candidate gene for cryptorchidism.

CONCLUSIONS

Detailed genetic profiling facilitates counselling and clinical management of the probands, and supports unaffected mutation carriers in the family for their reproductive decision making.

Novel NR5A1 mutations found in Chinese patients with 46, XY disorders of sex development

OBJECTIVE

To analyze nuclear receptor subfamily 5 group A member 1 (NR5A1) gene mutations in a cohort of Chinese patients with 46, XY Disorders of Sex Development (DSD).

METHODS

Sixty 46, XY DSD patients were recruited at Peking Union Medical College Hospital. Targeted next-generation and Sanger sequencing were performed to investigate pathogenic gene variants and validate NR5A1 gene variants, respectively. In silico tools and in vitro function studies were used to analyze the pathogenicity of rare variants. The clinical and endocrinological characteristics of patients with NR5A1 variants were retrospectively analyzed.

RESULTS

A total of four novel and three recurrent NR5A1 variants were identified in seven 46, XY DSD patients. These variants widely spread almost all the functional domains. Functional studies showed that novel mutations including p.S32N, p.N44del and p.G91D reduced transactivation of CYP11A1, while the other missense variant p.A168E did not impact protein function. All patients with NR5A1 rare variants had normal adrenal function and showed genital defects. Results of the genitalia examination showed female external genitalia (three patients), ambiguous external genitalia (two patients), female external genitalia with clitoromegaly (one patient), and hypospadias (one patient). All seven patients had bilateral testis and five of seven patients lacked Müllerian structures.

CONCLUSIONS

Four novel mutations in the NR5A1 gene were identified in our cohort with 46, XY DSD, expanding the spectrum of NR5A1 gene mutations. All patients with NR5A1 rare variants had normal adrenal function and showed genital defects.

Disrupted-in-Schizophrenia-1 is essential for normal hypothalamic-pituitary-interrenal (HPI) axis function

Psychiatric disorders arise due to an interplay of genetic and environmental factors, including stress. Studies in rodents have shown that mutants for Disrupted-In-Schizophrenia-1 (DISC1), a well-accepted genetic risk factor for mental illness, display abnormal behaviours in response to stress, but the mechanisms through which DISC1 affects stress responses remain poorly understood. Using two lines of zebrafish homozygous mutant for disc1, we investigated behaviour and functioning of the hypothalamic-pituitary-interrenal (HPI) axis, the fish equivalent of the hypothalamic-pituitary-adrenal (HPA) axis. Here, we show that the role of DISC1 in stress responses is evolutionarily conserved and that DISC1 is essential for normal functioning of the HPI axis. Adult zebrafish homozygous mutant for disc1 show aberrant behavioural responses to stress. Our studies reveal that in the embryo, disc1 is expressed in neural progenitor cells of the hypothalamus, a conserved region of the vertebrate brain that centrally controls responses to environmental stressors. In disc1 mutant embryos, proliferating rx3+ hypothalamic progenitors are not maintained normally and neuronal differentiation is compromised: rx3-derived ff1b+ neurons, implicated in anxiety-related behaviours, and corticotrophin releasing hormone (crh) neurons, key regulators of the stress axis, develop abnormally, and rx3-derived pomc+ neurons are disorganised. Abnormal hypothalamic development is associated with dysfunctional behavioural and neuroendocrine stress responses. In contrast to wild type siblings, disc1 mutant larvae show altered crh levels, fail to upregulate cortisol levels when under stress and do not modulate shoal cohesion, indicative of abnormal social behaviour. These data indicate that disc1 is essential for normal development of the hypothalamus and for the correct functioning of the HPA/HPI axis.

Clinical follow-up of the first SF-1 insufficient female patient

OBJECTIVE

Steroidogenic factor 1 (SF-1/NR5A1) plays a crucial role in regulating adrenal development, gonad determination and differentiation, and in the hypothalamic-pituitary control of reproduction and metabolism. In men (46, XY), it is known that mutations in SF-1/NR5A1 gene cause a wide phenotypic spectrum with variable degrees of undervirilization. In recent years, the role of SF-1 in the ovarian function was increasingly discussed and alterations in the gene were related to primary ovarian insufficiency. We describe the follow-up of a 46, XX affected woman with a SF-1 mutation and by comparing our case with the known manifestations reported in the literature, we try to further elucidate the function of SF-1 in the ovary.

RESULTS

During infancy, adrenal insufficiency was the only clinical sign of the loss-of-function as ovarian development and function seemed normal. To date, this young woman aged 16.5 years shows normal growth, normal BMI and psychomotor development, has a normal puberty and regular menstruation.

CONCLUSION

This report shows one, to date uniquely described, phenotypic variant of SF-1 mutation in a 46, XX affected person with adrenocortical insufficiency but no ovarian dysfunction nor disturbance of pubertal development. To follow the natural history of SF-1 mutation in a 46, XX individual will further shed light on its role in the ovarian function and thus will help to counsel affected patients in future.

A novel C-terminal truncating NR5A1 mutation in dizygotic twins

Nuclear receptor subfamily 5, group A, member 1 (NR5A1) is a nuclear receptor involved in gonadal and adrenal development. We identified a novel C-terminally truncating NR5A1 mutation, p.Leu423Trpfs*7, in dizygotic twins with 46,XY disorders of sex development. Our results highlight the functional importance of C-terminal region of NR5A1 and indicate that NR5A1 mutations can be associated with intrafamilial phenotypic variations, progressive testicular dysfunction, hypogonadotropic hypogonadism, and borderline adrenal dysfunction.

The role of next generation sequencing in understanding male and female sexual development: clinical implications

Next Generation Sequencing is revolutionising our understanding of variation in the human genome and as costs reduce the sequencing of patient's genomes is become more routine. Areas covered: Here, we review the current challenges in the field and some of the efforts that are underway to resolve them. We describe how these technologies are impacting on our understanding of human sex development and the profound clinical implications of these technologies on conditions such as Disorders of Sex Development (DSD). Expert commentary: The sheer wealth of genomic data is generating new challenges-some are technical such as variant calling, or predicting the functional consequence of a variant-whereas others are more profound, such as establishing the link between extensive genomic information and the clinical presentation. Predicting disease phenotypes from genetic sequences is often extremely difficult because the genotype-phenotype relationship has proven to be far more complex than anticipated.

Aetiological coding sequence variants in non-syndromic premature ovarian failure: From genetic linkage analysis to next generation sequencing

Premature ovarian failure (POF) is a frequent pathology affecting 1-1.5% of women under 40 years old. Despite advances in diagnosing and treating human infertility, POF is still classified as being idiopathic in 50-80% of cases, strongly suggesting a genetic origin for the disease. Different types of autosomal and X-linked genetic anomalies can originate the phenotype in syndromic and non-syndromic POF cases. Particular interest has been focused on research into non-syndromic POF causative coding variants during the past two decades. This has been based on the assumption that amino acid substitutions might modify the intrinsic physicochemical properties of functional proteins, thereby inducing pathological phenotypes. In this case, a restricted number of mutations might originate the disease. However, like other complex pathologies, POF might result from synergistic/compensatory effects caused by several low-to-mildly drastic mutations which have frequently been classified as non-functional SNPs. Indeed, reproductive phenotypes can be considered as quantitative traits resulting from the subtle interaction of many genes. Although numerous sequencing projects have involved candidate genes, only a few coding mutations explaining a low percentage of cases have been described. Such apparent failure to identify aetiological coding sequence variations might have been due to the inherent molecular complexity of mammalian reproduction and to the difficulty of simultaneously analysing large genomic regions by Sanger sequencing. The purpose of this review is to present the molecular and cellular effects caused by non-synonymous mutations which have been formally associated, by functional tests, with the aetiology of hypergonadotropic non-syndromic POF. Considerations have also been included regarding the polygenic nature of reproduction and POF, as well as future approaches for identifying novel aetiological genes based on next generation sequencing (NGS).

Effects of deletion of mutant huntingtin in steroidogenic factor 1 neurons on the psychiatric and metabolic phenotype in the BACHD mouse model of Huntington disease

Psychiatric and metabolic features appear several years before motor disturbances in the neurodegenerative Huntington’s disease (HD), caused by an expanded CAG repeat in the huntingtin (HTT) gene. Although the mechanisms leading to these aspects are unknown, dysfunction in the hypothalamus, a brain region controlling emotion and metabolism, has been suggested. A direct link between the expression of the disease causing protein, huntingtin (HTT), in the hypothalamus and the development of metabolic and psychiatric-like features have been shown in the BACHD mouse model of HD. However, precisely which circuitry in the hypothalamus is critical for these features is not known. We hypothesized that expression of mutant HTT in the ventromedial hypothalamus, an area involved in the regulation of metabolism and emotion would be important for the development of these non-motor aspects. Therefore, we inactivated mutant HTT in a specific neuronal population of the ventromedial hypothalamus expressing the transcription factor steroidogenic factor 1 (SF1) in the BACHD mouse using cross-breeding based on a Cre-loxP system. Effects on anxiety-like behavior were assessed using the elevated plus maze and novelty-induced suppressed feeding test. Depressive-like behavior was assessed using the Porsolt forced swim test. Effects on the metabolic phenotype were analyzed using measurements of body weight and body fat, as well as serum insulin and leptin levels. Interestingly, the inactivation of mutant HTT in SF1-expressing neurons exerted a partial positive effect on the depressive-like behavior in female BACHD mice at 4 months of age. In this cohort of mice, no anxiety-like behavior was detected. The deletion of mutant HTT in SF1 neurons did not have any effect on the development of metabolic features in BACHD mice. Taken together, our results indicate that mutant HTT regulates metabolic networks by affecting hypothalamic circuitries that do not involve the SF1 neurons of the ventromedial hypothalamus.

Characteristic testicular histology is useful for the identification of NR5A1 gene mutations in prepubertal 46,XY patients

BACKGROUND

Individuals with NR5A1 mutations encoding steroidogenic factor-1 (SF1) develop a phenotypically broad range of disorders of sexual development (DSD). Based on a literature review, we noted that hypoplastic seminiferous tubules and the emergence of Leydig cells with vacuolar cytoplasms are seen predominantly in the majority of individuals with NR5A1 mutations.

AIM

The aim of this study was to address whether the histopathological characteristics of the testis can be a biomarker for 46,XY individuals with NR5A1 mutations.

DESIGN

In order to ascertain whether or not the histological features were the characteristics of NR5A1 mutations, we screened the testicular histology of 242 patients with 46,XY DSD and then subsequently assessed NR5A1 mutations.

RESULT

Of 242 patients with 46,XY DSD, 6 patients matched histological testicular features: a reduced number of thin seminiferous tubules and focal aggregations of Leydig cells that contained cytoplasmic lipid droplets. All 6 patients had NR5A1 mutations. These histological features were distinct from those of other DSD. Thus, this unique testicular histology is useful for identifying NR5A1 mutations in 46,XY patients with DSD before puberty.

Long-Term Follow-Up of Patients with 46,XY Partial Gonadal Dysgenesis Reared as Males

Background/Aims. Studies on 46,XY partial gonadal dysgenesis (PGD) have focused on molecular, gonadal, genital, and hormone features; little is known about follow-up. Our aim was to analyze long-term outcomes of PGD. Methods. Retrospective longitudinal study conducted at a reference service in Brazil. Ten patients were first evaluated in the 1990s and followed up until the 2010s; follow-up ranged from 13.5 to 19.7 years. All were reared as males and had at least one scrotal testis; two bore NR5A1 mutations. Main outcomes were: associated conditions, pubertal development, and growth. Results. All patients had normal motor development but three presented cognitive impairment; five had various associated conditions. At the end of the prepubertal period, FSH was high or high-normal in 3/6 patients; LH was normal in all. At the last evaluation, FSH was high or high-normal in 8/10; LH was high or high-normal in 5/10; testosterone was decreased in one. Final height in nine cases ranged from -1.57 to 0.80 SDS. All had spontaneous puberty; only one needed androgen therapy. Conclusions. There is good prognosis for growth and spontaneous pubertal development but not for fertility. Though additional studies are required, screening for learning disabilities is advisable.

Novel NR5A1 missense mutation in premature ovarian failure: detection in han chinese indicates causation in different ethnic groups

Background

The etiology of most premature ovarian failure (POF) cases is usually elusive. Although genetic causes clearly exist and a likely susceptible region of 8q22.3 has been discovered, no predominant explanation exists for POF. More recently, evidences have indicated that mutations in NR5A1 gene could be causative for POF. We therefore screened for mutations in the NR5A1 gene in a large cohort of Chinese women with non-syndromic POF.

Methods

Mutation screening of NR5A1 gene was performed in 400 Han Chinese women with well-defined 46,XX idiopathic non-syndromic POF and 400 controls. Subsequently, functional characterization of the novel mutation identified was evaluated in vitro.

Results

A novel heterozygous missense mutation [c.13T>G (p.Tyr5Asp)] in NR5A1 was identified in 1 of 384 patients (0.26%). This mutation impaired transcriptional activation on Amh, Inhibin-a, Cyp11a1 and Cyp19a1 gene, as shown by transactivation assays. However, no dominant negative effect was observed, nor was there impact on protein expression and nuclear localization.

Conclusions

This novel mutation p.Tyr5Asp, in a novel non-domain region, is presumed to result in haploinsufficiency. Irrespectively, perturbation in NR5A1 is not a common explanation for POF in Chinese.