Distribution of marker‐Y chromosome containing cells in different tissues of a Turner mosaic patient with mixed gonadal dysgenesis

We here describe a 12-year-old girl with numerous Turner stigmata and virilized external genitalia. Chromosome analysis of PHA stimulated lymphocytes using different banding techniques revealed a 45,X/46,X,+mar Turner mosaicism with the prominent marker present in about 90% of the blood cells. A PCR-based analysis using a set of 9 STS from different regions of the human Y chromosome indicated the presence of Y chromosomal material with a deletion breakpoint most likely within deletion interval 6. Because of the risk of gonadoblastoma for Turner patients carrying Y chromosomal material, and clinical indications of functional testicular tissue, a gonadectomy in addition to surgical correction of the external genitalia was performed. The histological analysis of the gonads showed a mixture of testicular tissue and ovarian stroma, thus indicating mixed gonadal dysgenesis. Fibroblasts from skin and different parts of the gonads were cytogenetically analyzed and showed a variable distribution of the Y-derived marker between 4% in skin, 11-31% in gonadal tissue and up to 90% in peripheral lymphocytes.