Microsatellite instability in gonadal tumors of XY pure gonadal dysgenesis patients.

To investigate genetic alternation accompanied by malignant transformation in gonadal tumors of XY pure gonadal dysgenesis patients, we investigated microsatellite instability in the hMSH1, hMSH2, TP53, and DCC loci, and ras mutations in two patients. The gonadal tumors from the patients were combined gonadoblastoma and dysgerminoma. Microsatellite instability and/or loss of heterozygotes (LOH) at hMSH1, hMSH2, and TP53 were detected in the dysgerminoma lesions of the both patients, but were not observed in any normal tissues. In the analyses of the H-, K-, or N-ras genes, where specific mutations have been frequently reported, no mutations were observed in the tumors. It is suggested therefore that microsatellite instability plays an important role in malignant transformation of gonadal tumors in patients with XY pure gonadal dysgenesis.