XY-GONADAL-DYSGENESIS AND GONADOBLASTOMA - A STUDY IN 2 SISTERS WITH A CRYPTIC DELETION OF THE Y-CHROMOSOME INVOLVING THE SRY GENE

This paper reports a case of XY gonadal dysgenesis in two sisters. Bot h patients presented an eunochoid female phenotype with normal externa l genitalia. At laparotomy, the elder sister was found to have bilater al gonadoblastoma. Cytogenetic studies, which included G and C banding and in situ hybridization, showed that the patients had an apparently normal 46, XY karyotype. PCR analyses revealed absence of the conserv ed portion (HMG box) of the SRY gene and of the Y chromosome pseudoaut osomal boundary region sequence in both patients. The presence of the ZFY sequence was detected by Southern hybridization in the two affecte d sisters. The patients' father (46, XY, no mosaicism detected in peri pheral blood lymphocytes) was positive for SRY and ZFY sequences. The occurrence of gonadoblastoma is discussed in terms of the genetic fact ors that may lead to tumor development.