BACKGROUND: The Ullrich-Turner syndrome (UTS) demonstrates a great clinical variability according to the cytogenetic and molecular genetic findings in various tissues. In few cases the karyotype reveals the presence of an additional Y-bearing cell line which is referred to as a borderline case of mixed gonadal dysgenesis. In this condition, Turner specific stigmata occur in about half of the cases. PATIENT: A 10 year-old girl with short stature and only a few other signs of Turner syndrome and hypertrophic clitoris revealed 45,X/46,X,idic(Yq) mosaicism with 41% 46,X,idic(Yq) cells in a blood lymphocyte culture. METHODS AND RESULTS: Fluorescence in situ hybridisation (FISH) technique, using alpha-satellite Y-chromosome specific probe for locus DYZ3, confirmed the isodicentric character of this structurally abnormal Y chromosome. Polymerase chain reaction (PCR) analysis using primers for eight loci along the Y chromosome including SRY (Sex determining Region, Y gene) were positive for all loci tested, indicating that sequences from the long arm, centromere and most of the short arm of the Y chromosome are present. CONCLUSIONS: As patients with normal or rearranged Y chromosome have an increased risk of developing gonadal neoplasia prophylactic gonadectomy 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 and molecular genetic investigations in the definition of mosaicism in Turner's syndrome.
BACKGROUND: The Ullrich-Turner syndrome (UTS) demonstrates a great clinical variability according to the cytogenetic and molecular genetic findings in various tissues. In few cases the karyotype reveals the presence of an additional Y-bearing cell line which is referred to as a borderline case of mixed gonadal dysgenesis. In this condition, Turner specific stigmata occur in about half of the cases. PATIENT: A 10 year-old girl with short stature and only a few other signs of Turner syndrome and hypertrophic clitoris revealed 45,X/46,X,idic(Yq) mosaicism with 41% 46,X,idic(Yq) cells in a blood lymphocyte culture. METHODS AND RESULTS: Fluorescence in situ hybridisation (FISH) technique, using alpha-satellite Y-chromosome specific probe for locus DYZ3, confirmed the isodicentric character of this structurally abnormal Y chromosome. Polymerase chain reaction (PCR) analysis using primers for eight loci along the Y chromosome including SRY (Sex determining Region, Y gene) were positive for all loci tested, indicating that sequences from the long arm, centromere and most of the short arm of the Y chromosome are present. CONCLUSIONS: As patients with normal or rearranged Y chromosome have an increased risk of developing gonadal neoplasia prophylactic gonadectomy 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 and molecular genetic investigations in the definition of mosaicism in Turner's syndrome.