The presence of mosaic 45,X/46,XY is a very rare chromosomal anomaly. The presence of Y chromatin in individulas with Ullrich-Turner syndrome confers a risk for gonadoblastoma. The case presented at short stature, primary amenorrhea and hypoplasic uterus. Karyotype was determined as 45,X/46,XY by cytogenetic analysis of peripheral blood. We performed molecular genetic analysis for Y chromosomal loci (SRY, ZFY, SY84, SY86, SY127, SY134, SY254, SY255) both blood leukocytes and paraffin-embedded gonadal tissue. Case was positive for all sequences tested and developed an bilateral endodermal sinus tumor diagnosed by a pathologist. Adequate counseling regarding a gonadectomy should be given because of the high proportion (33%) of gonadal tumors in patients with Y-chromosome sequences. It is first report about bilateral EST in a UTS patient with 45,X/46XY karyotype according to our knowledge.

Keywords: Ullrich-Turner syndrome, Y chromosomal loci, endodermal sinus tumor