SRY-positive 45,X/46,XY karyotype in a phenotypically Turner-like Chinese adolescent female with ovarian dysgerminoma and gonadoblastoma.

Objectives: 45,X/46,XY mosaicism is a rare condition with clinical and genetic heterogeneity and have a greatly increased risk of developing germ cell tumors. We describe a rare 45,X/46,XY Chinese girl with malignant tumors, especially focusing on the molecular genetics of gonadal tumor.

Case presentation: We report a phenotypically Turner-like Chinese adolescent girl who presented primary amenorrhea and a pelvic mass as the chief complaint, which finally demonstrated dysgerminoma replacing the left gonad and gonadoblastoma arising from right gonad respectively. Her chromosome karyotype was 45,X(4)/46,XY(46); Y-chromosome microdeletions in AZFb regions were found on gonadal DNA rather than peripheral blood lymphocyte (PBL) DNA, while no variants were found in the promoter and coding region of SRY gene in both PBL and gonadal tissues. She underwent bilateral gonadectomy; no recurrence or serious complications were identified after 3 years of follow-up.

Conclusions: This case emphasizes the probable correlation between Y chromosome microdeletions in gonadal tissue and the severity of the phenotype in patients with 45,X/46,XY mosaicism and highlights the importance of clinical genetic testing at the chromosomal and molecular level.