Gonadal tumor development in 46,XX disorders of gonadal development

BACKGROUND

Differences/disorders of sex development (DSD) are congenital conditions in which the development of chromosomal, gonadal, or anatomical sex is atypical.

OBJECTIVE

The aim of this study is to report the histological characteristics and immunoexpression patterns of gonadal parenchyma in patients with 46,XX testicular and ovotesticular DSD, with a focus on the detection of germ cell malignancies.

DESIGN

Inclusion criteria were SRY-negative 46,XX testicular and ovotesticular DSD with available samples from gonadal biopsy or gonadectomy for the review of histological findings. Gonadal histology was assessed on hematoxylin and eosin-stained sections and immunohistochemical analysis. Histopathological criteria from the last World Health Organization classification of urogenital tumors were used to identify undifferentiated gonadal tissue, gonadoblastoma, and dysgerminoma.

RESULTS

Median age at first histological evaluation of gonadal samples was 1.46 years (range: 0.16-16 years). Totally 15 patients were classified as ovotesticular and only 1 as testicular DSD. Most individuals had bilateral ovotestes (12/15). No histological alterations were found in the ovarian parenchyma, while signs of dysgenesis were seen in all cases of testicular parenchyma. In 4/15 ovotesticular DSD, a prepubertal biopsy failed to identify ovarian parenchyma. We detected early prepubertal preinvasive and invasive malignancies in this cohort (five patients had undifferentiated gonadal tissue, five gonadoblastoma, and one dysgerminoma).

CONCLUSION

46,XX disorders of gonadal development are historically considered at a low risk for germ cell cancer, and the need for assessment of gonadal histology has been questioned. The finding of early germ cell malignancies in our cohort brings awareness and needs further research.

Female-to-male sex reversal associated with unique Xp21.2 deletion disrupting genomic regulatory architecture of the dosage-sensitive sex reversal region

BACKGROUND

The XX male disorder of sex development (DSD) is a rare condition that is most commonly associated with the presence of the SRY gene on one of the X chromosomes due to unequal crossing-over between sex chromosomes during spermatogenesis. However, in about 20% of the XX male individuals, SRY is missing, although these persons have at least some testis differentiation. The genetic basis of genital ambiguity and the mechanisms triggering testis development in such patients remain unknown.

METHODS

The proband with 46,XX SRY-negative testicular DSD was screened for point mutations by whole exome sequencing and CNVs using a high-resolution DSD gene-targeted and whole genome array comparative genomic hybridisation. The identified Xp21.2 genomic alteration was further characterised by direct sequencing of the breakpoint junctions and bioinformatics analysis.

RESULTS

A unique, 80 kb microdeletion removing the regulatory sequences and the NR0B1 gene was detected by microarray analysis. This deletion disturbs the human-specific genomic architecture of the Xp21.2 dosage-sensitive sex (DSS) reversal region in the XX patient with male-appearing ambiguous genitalia and ovotestis.

CONCLUSIONS

Duplication of the DSS region containing the MAGEB and NR0B1 genes has been implicated in testis repression and sex reversal. Identification of this microdeletion highlights the importance of genomic integrity in the regulation and interaction of sex determining genes during gonadal development.