Familial forms of disorders of sex development may be common if infertility is considered a comorbidity

A Risk of Gonadoblastoma in Familial Swyer Syndrome-A Case Report and Literature Review

A complete gonadal dysgenesis (CGD) with 46,XY karyotype is known as the Swyer syndrome and belongs to the group of 46,XY differences of sex development (DSD). The main problem in patients with Swyer syndrome is the delayed puberty and primary amenorrhea. Moreover, intrabdominal dysgenetic gonads in the patient with genetic material of a Y chromosome may conduce to the development of gonadal tumors, such as gonadoblastoma or germinoma. The management of such patients is based on preventive excision of dysgenetic gonads and long-term hormonal replacement therapy. Sporadic cases are considered more common than familial cases. This paper presents two siblings with Swyer syndrome in whom gonadoblastoma was found. A thorough review of familial CGD with 46,XY DSD in the literature from the last 15 years suggests that the risk of gonadal tumors could be increased in familial compared to sporadic cases (66.6% vs. 15-45%, respectively).

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.

Genomics of Recombination Rate Variation in Temperature-Evolved Drosophila melanogaster Populations

Meiotic recombination is a critical process that ensures proper segregation of chromosome homologs through DNA double-strand break repair mechanisms. Rates of recombination are highly variable among various taxa, within species, and within genomes with far-reaching evolutionary and genomic consequences. The genetic basis of recombination rate variation is therefore crucial in the study of evolutionary biology but remains poorly understood. In this study, we took advantage of a set of experimental temperature-evolved populations of Drosophila melanogaster with heritable differences in recombination rates depending on the temperature regime in which they evolved. We performed whole-genome sequencing and identified several chromosomal regions that appear to be divergent depending on temperature regime. In addition, we identify a set of single-nucleotide polymorphisms and associated genes with significant differences in allele frequency when the different temperature populations are compared. Further refinement of these gene candidates emphasizing those expressed in the ovary and associated with DNA binding reveals numerous potential candidate genes such as Hr38, EcR, and mamo responsible for observed differences in recombination rates in these experimental evolution lines thus providing insight into the genetic basis of recombination rate variation.

Identification of gene variants in 130 Han Chinese patients with hypospadias by targeted next-generation sequencing

Background

Hypospadias is a common congenital malformation of male external genitalia, which mainly manifests as an abnormal urethral opening on the ventral side of the penis. The etiology and clinical phenotype of hypospadias is highly heterogeneous, and its clinical diagnosis is challenging. Currently, over 70% of patients have an unknown etiology. Here, we performed a targeted analysis of gene mutations in 130 patients with hypospadias of unknown etiology to find the precise genetic cause.

Methods

We developed a targeted next‐generation sequencing (NGS) panel, encompassing the exon coding regions of 105 genes involved in external genitalia and urogenital tract development and performed sequencing analysis on 130 children with hypospadias of unknown etiology.

Results

In total, 25 patients with hypospadias (19.2%) were found to have 20 mutations among the nine genes involved in external genitalia and urogenital tract development, including 16 reported and four novel mutation sites. Twenty‐two patients (16.9%) had diagnostic variants. Multiple genetic mutations were identified in three of the 25 patients. Hypospadias combined with micropenis was the most common phenotype (68%) in 25 patients.

Conclusions

Higher frequency mutations were identified in SRD5A2 (52%) and AR (24%) in our patient cohort. Middle or posterior hypospadias with micropenis may be significant indicators of genetic variations. Polygenic inheritance may be a rare genetic cause of hypospadias.

Baseline Characteristics of Infants With Atypical Genital Development: Phenotypes, Diagnoses, and Sex of Rearing

Purpose

Little is known about the phenotypes, diagnoses, and sex of rearing of infants with atypical genital development in the United States. As part of a multicenter study of these infants, we have provided a baseline report from US difference/disorder of sex development clinics describing the diagnoses, anatomic features, and sex of rearing. We also determined whether consensus guidelines are followed for sex designation in the United States.

Methods

Eligible participants had moderate-to-severe genital atypia, were aged <3 years, and had not undergone previous genitoplasty. Karyotype, genetic diagnosis, difference/disorder of sex development etiology, family history, and sex of rearing were collected. Standardized examinations were performed.

Results

Of 92 subjects, the karyotypes were 46,XX for 57%, 46,XY for 34%, and sex chromosome abnormality for 9%. The median age at the baseline evaluation was 8.8 months. Most 46,XX subjects (91%) had congenital adrenal hyperplasia (CAH) and most 46,XY subjects (65%) did not have a known diagnosis. Two individuals with CAH underwent a change in sex of rearing from male to female within 2 weeks of birth. The presence of a uterus and shorter phallic length were associated with female sex of rearing. The most common karyotype and diagnosis was 46,XX with CAH, followed by 46,XY with an unknown diagnosis. Phenotypically, atypical genitalia have been most commonly characterized by abnormal labioscrotal tissue, phallic length, and urethral meatus location.

Conclusions

An increased phallic length was positively associated with rearing male. Among the US centers studied, sex designation followed the Consensus Statement recommendations. Further study is needed to determine whether this results in patient satisfaction.

At the Crossroads of Fate-Somatic Cell Lineage Specification in the Fetal Gonad

The reproductive endocrine systems are vastly different between males and females. This sexual dimorphism of the endocrine milieu originates from sex-specific differentiation of the somatic cells in the gonads during fetal life. Most gonadal somatic cells arise from the adrenogonadal primordium. After separation of the adrenal and gonadal primordia, the gonadal somatic cells initiate sex-specific differentiation during gonadal sex determination with the specification of the supporting cell lineages: Sertoli cells in the testis vs granulosa cells in the ovary. The supporting cell lineages then facilitate the differentiation of the steroidogenic cell lineages, Leydig cells in the testis and theca cells in the ovary. Proper differentiation of these cell types defines the somatic cell environment that is essential for germ cell development, hormone production, and establishment of the reproductive tracts. Impairment of lineage specification and function of gonadal somatic cells can lead to disorders of sexual development (DSDs) in humans. Human DSDs and processes for gonadal development have been successfully modeled using genetically modified mouse models. In this review, we focus on the fate decision processes from the initial stage of formation of the adrenogonadal primordium in the embryo to the maintenance of the somatic cell identities in the gonads when they become fully differentiated in adulthood.

Functional characterization of novel NR5A1 variants reveals multiple complex roles in disorders of sex development

Variants in the NR5A1 gene encoding SF1 have been described in a diverse spectrum of disorders of sex development (DSD). Recently, we reported the use of a targeted gene panel for DSD where we identified 15 individuals with a variant in NR5A1, nine of which are novel. Here, we examine the functional effect of these changes in relation to the patient phenotype. All novel variants tested had reduced trans‐activational activity, while several had altered protein level, localization, or conformation. In addition, we found evidence of new roles for SF1 protein domains including a region within the ligand binding domain that appears to contribute to SF1 regulation of Müllerian development. There was little correlation between the severity of the phenotype and the nature of the NR5A1 variant. We report two familial cases of NR5A1 deficiency with evidence of variable expressivity; we also report on individuals with oligogenic inheritance. Finally, we found that the nature of the NR5A1 variant does not inform patient outcomes (including pubertal androgenization and malignancy risk). This study adds nine novel pathogenic NR5A1 variants to the pool of diagnostic variants. It highlights a greater need for understanding the complexity of SF1 function and the additional factors that contribute.