A TURNER-LIKE PHENOTYPE IN A GIRL WITH AN ISODICENTRIC FLUORESCENT Y-CHROMOSOME MOSAICISM

Background The Ullrich-Turner syndrome (UTS) demonstrates a great clin ical variability according to the cytogenetic and molecular genetic fi ndings in various tissues. In few cases the karyotype reveals the pres ence of an additional Y-bearing cell line which is referred to as a bo rderline case of mixed gonadal dysgenesis. In this condition, Turner s pecific stigmata occur in about half of the cases. Patient A 10 year-o ld girl with short stature and only a few other signs of Turner syndro me and hypertrophic clitoris revealed 45,X/46,X,idic(Yq) mosaicism wit h 41% 46,X,idic(Yq) cells in a blood lymphocyte culture. Methods and r esults Fluorescence in situ hybridisation (FISH) technique, using alph a-satellite Y-chromosome specific probe for locus DYZ3, confirmed the isodicentric character of this structurally abnormal Y chromosome. Pol ymerase chain reaction (PCR) analysis using primers for eight loci alo ng the Y chromosome including SRY (Sex determining Region, Y gene) wer e positive for all loci tested, indicating that sequences from the lon g arm, centromere and most of the short arm of the Y chromosome are pr esent. Conclusions As patients with normal or rearranged Y chromosome have an increased risk of developing gonadal neoplasia prophylactic go nadectomy was performed in our patient. No evidence for gonadoblastoma was found on her streak-like gonads, but they showed some evidence of tubular formation. This paper points out the impact of cytogenetic an d molecular genetic investigations in the definition of mosaicism in T urner's syndrome.