Broad-spectrum XX and XY gonadal dysgenesis in patients with a homozygous L193S variant in PPP2R3C

Context: Homozygous and heterozygous variants in PPP2R3C are associated with syndromic 46,XY complete gonadal dysgenesis (MEGD syndrome), and impaired spermatogenesis, respectively. This study expands the role of PPP2R3C in the aetiology of gonadal dysgenesis (GD). Method: We sequenced the PPP2R3C gene in four new patients from three unrelated families. The clinical, laboratory and molecular characteristics were investigated. We have also determined the requirement for Ppp2r3c in mice (C57BL6/N) using CRISPR/Cas9 genome editing. Results: A homozygous c.578T>C (p.L193S) PPP2R3C variant was identified in one 46,XX girl with primary gonadal insufficiency, 2 girls with 46,XY complete GD, and one undervirilized boy with 46,XY partial GD. The patients with complete GD had low gonadal and adrenal androgens, low AMH, and high FSH and LH concentrations. All patients manifested characteristic features of MEGD syndrome. Heterozygous Ppp2r3c knockout mice appeared overtly normal and fertile. Inspection of homozygous embryos at 14.5, 9.5 and 8.5 days post coitum revealed evidence of dead embryos. We conclude that loss of function of Ppp2r3c is not compatible with viability in mice and results in embryonic death from 7.5 dpc or earlier. Conclusion: Our data indicate essential roles for PPP2R3C in mouse and human development. Germline homozygous variants in human PPP2R3C are associated with distinctive syndromic GD of varying severity in both 46,XY and 46,XX individuals.

DMRT1: An Ancient Sexual Regulator Required for Human Gonadogenesis

Transcriptional regulators related to the invertebrate sexual regulators <i>doublesex</i> and <i>mab-3</i> occur throughout metazoans and control sex in most animal groups. Seven of these <i>DMRT</i> genes are found in mammals, and mouse genetics has shown that one, <i>Dmrt1</i>, plays a crucial role in testis differentiation, both in germ cells and somatic cells. Deletions and, more recently, point mutations affecting human <i>DMRT1</i> have demonstrated that its heterozygosity is associated with 46,XY complete gonadal dysgenesis. Most of our detailed knowledge of DMRT1 function in the testis, the focus of this review, derives from mouse studies, which have revealed that DMRT1 is essential for male somatic and germ cell differentiation and maintenance of male somatic cell fate after differentiation. Moreover, ectopic DMRT1 can reprogram differentiated female granulosa cells into male Sertoli-like cells. The ability of DMRT1 to control sexual cell fate likely derives from at least 3 properties. First, DMRT1 functionally collaborates with another key male sex regulator, SOX9, and possibly other proteins to maintain and reprogram sexual cell fate. Second, and related, DMRT1 appears to function as a pioneer transcription factor, binding “closed” inaccessible chromatin and promoting its opening to allow binding by other regulators including SOX9. Third, DMRT1 binds DNA by a highly unusual form of interaction and can bind with different stoichiometries.

Dysgerminoma presenting at fifty, consequence to undiagnosed Swyer syndrome

Swyer syndrome or XY complete gonadal dysgenesis (CGD) is a rare disorder of sex development (DSD) characterized by presence of dysgenetic gonads in a phenotypically female patient with a male karyotype. Usually Swyer syndrome is diagnosed following appropriate evaluation for amenorrhea in adolescence and prophylactic gonadectomy is done as these patients have high risk of developing malignancy in their dysgenetic gonads. Here we presented patient who presented later in life with ovarian malignancy which turned out to be a consequence of undiagnosed Swyer syndrome. Her case exemplifies that fact that improper evaluation of primary amenorrhea in adolescence and omission to do prophylactic bilateral gonadectomy led to her presenting with malignancy at this advanced age. Therefore, be aware to not let Swyer syndrome go undiagnosed and mismanaged.

Expanding DSD Phenotypes Associated with Variants in the DEAH-Box RNA Helicase DHX37

Missense variants in the RNA-helicase DHX37 are associated with either 46,XY gonadal dysgenesis or 46,XY testicular regression syndrome (TRS). DHX37 is required for ribosome biogenesis, and this subgroup of XY DSD is a new human ribosomopathy. In a cohort of 140 individuals with 46,XY DSD, we identified 7 children with either 46,XY complete gonadal dysgenesis or 46,XY TRS carrying rare or novel DHX37 variants. A novel p.R390H variant within the RecA1 domain was identified in a girl with complete gonadal dysgenesis. A paternally inherited p.R487H variant, previously associated with a recessive congenital developmental syndrome, was carried by a boy with a syndromic form of 46,XY DSD. His phenotype may be explained in part by a novel homozygous loss-of-function variant in the <i>NGLY1</i> gene, which causes a congenital disorder of deglycosylation. Remarkably, a homozygous p.T477H variant was identified in a boy with TRS. His fertile father had unilateral testicular regression with typical male genital development. This expands the DSD phenotypes associated with DHX37. Structural analysis of all variants predicted deleterious effects on helicase function. Similar to all other known ribosomopathies, the mechanism of pathogenesis is unknown.

Complete gonadal dysgenesis analysis in the population of Latvia: malignant outcomes and a review of literature

Background and aim. Complete gonadal dysgenesis or Swyer syndrome is a rare genetic disorder characterized by 46,XY karyotype and female phenotype with undeveloped streak gonads and high malignancy risk. The condition usually manifests in teenage and young adults with delayed puberty and primary amenorrhea. The purpose of this study was to investigate the incidence and potential malignant outcomes of complete gonadal dysgenesis in Latvia. Methods. 37 patients were included in a retrospective study from 1996 to 2016. In fifteen cases, additional patient information was available. Information from medical records was collected on age at the time of diagnosis: anamnesis data, laboratory results, histology of gonads, and treatment. Results. Complete gonadal dysgenesis with karyotype 46,XY was proven in 36 (97.3%) cases and one (2.7%) case with karyotype 47,XY,+21. The average age of patients at the time of diagnosis was 15.4 ± 8.0 years. The study included 15 cases: eight patients (53.3%) were investigated for primary amenorrhea, and incomplete development of secondary sexual characteristics, 5 patients (33.3%) with abdominal pain and lower abdominal mass, 2 patients (13.3%) were diagnosed at birth. Gonadectomy was performed in 12 cases (80%). The median time between diagnosis and gonadectomy was 0.4 ± 4.3 years. The histopathology results from the gonadal biopsy showed malignancy in 7 cases (58.3%). The most commonly diagnosed tumors were dysgerminoma and gonadoblastoma. Conclusion. Early diagnosis of Swyer syndrome is necessary in view of the risk of malignancy that can develop at a young age. In several cases, the diagnosis of the syndrome was made only after the malignant process development. The study showed the median time between diagnosis and gonadectomy was suboptimal. Therefore, women with amenorrhea and lack of secondary sexual characteristics require careful investigation.

Homozygous DMRT1 mutation c.967G>A found in a Chinese patient with 46,XY complete gonadal dysgenesis and review of literature

A Chinese woman with 46,XY CGD was diagnosed by clinicopathologic findings . A homozygous mutation c.967G>A(p. Val323Ile) in the DMRT1 gene was detected in the patient by WES. As far as we know, this is the first case of 46,XY CGD caused by a homozygous mutation in the DMRT1 gene.

Association between Down Syndrome and Disorders of Sex Development: Report of Three Cases and Review of 188 Cases in the Literature

In this study, we present 3 cases of Down syndrome (DS) associated with disorders/differences of sex development (DSD) and review the literature on this topic. Case 1: 1-year-old child with male genitalia and DS phenotype, 47,XX,+21 karyotype and testicular DSD. Case 2: 11-month-old child with male genitalia and few DS dysmorphisms, 45,X/47,XY,+21 karyotype, and mixed gonadal dysgenesis. Case 3: 4-month-old child with female genitalia and DS phenotype, 47,XY,+21 karyotype and XY complete gonadal dysgenesis. In the literature, among 188 patients, 107 (57%) had Klinefelter syndrome and 61 (33%) Turner syndrome, 12 (6%) had mixed gonadal dysgenesis, 2 (1%) had partial androgen insensitivity, 2 (1%) ovotesticular DSD, and the others had congenital adrenal hyperplasia, XY partial gonadal dysgenesis, XY complete gonadal dysgenesis, and complete androgen insensitivity (1 case each). A typical DS phenotype was found in all individuals of the revision, with the exception of one case, but DSD features were not always reported. In conclusion, the association of DS with sex chromosome DSD is the most frequently observed, whereas associations with 46,XX and 46,XY DSD is extremely rare.