Background: Turner syndrome (TS) is one of the most common genetic disorders in females and occurs in phenotypic females who are missing all or part of one sex chromosome. While the most common mosaic forms of the disorder are 45,X/46,XX and 45,X/46,Xiq, mosaicism for cells containing Y chromosome material is well documented.
Objective and hypotheses: Owing to increased risk of gonadoblastoma (GB), current recommendations are for elective gonadectomy following diagnosis. But there are no recommendations on lower age limits.
Method: A review of TS patients attending the Paediatric Endocrinology Clinic (n=9) was conducted specifically looking for those with mosaicism for Y chromosome (TSMY). Three cases were identified and all underwent elective gonadectomy.
Results: Case 1 was diagnosed with TSMY at 2 years. Peripheral blood karyotype showed mosaicism for 45,X (25 cells) and an isodicentric Y chromosome made of Yp and proximal Yq material (25 cells). Gonadectomy at 6 years revealed extensive unilateral GB. Interphase FISH of the GB tissue showed isodicentric Y chromosome in 43% of GB cells. Case 2 presented with dysmorphic features at birth. G banded karyotype and interphase FISH of blood showed 45,X in 95% and 47,XY+18 (Edwards syndrome) in 5% of cells analysed. Interphase FISH of buccal cells showed 45,X only. Gonadectomy at 13 months revealed bilateral GB, interphase FISH was similar to blood: 45,X(86%), 47,XY+18(14%). Case 3 presented with severe neonatal aortic stenosis. Peripheral blood karyotype showed 45,X (29 cells) and a pseudoisocentric Y chromosome with breakpoint at Yq11.23 (six cells), confirmed on buccal and skin karyotyping. Gonadectomy revealed unilateral GB, karyotype pending.
Conclusion: All three patients with TSMY were found to have GB at elective gonadectomy. This highlights early age of occurrence of GB despite low mosaicism for SRY cell lines and would support a recommendation for early surgery in such cases, regardless of age.
18 Sep 2014 - 20 Sep 2014