Unusual mixed gonadal dysgenesis associated with Müllerian duct persistence, polygonadia, and a 45,X/46,X,idic(Y)(p) karyotype.

Mixed gonadal dysgenesis (MGD) is a developmental anomaly in which most of the patients have a dysgenetic testis, a contralateral streak and a 45,X/46,XY karyotype. This entity involves an heterogeneous group of gonadal and phenotypic abnormalities with a wide clinical spectrum. The phenotype depends on the ratio of testicular tissue which induces virilization. Although the karyotype in these patients is 45,X/46,XY, no genotype-phenotype correlation has been found to date. Müllerian ducts persistence (MDP) in MGD is rare; however, four patients with both entities and different karyotypes have been described. Here we present the data on a newborn patient with an atypical MGD associated with MDP, two left testes, a gonadal streak on the right, and absence of Wolffian derivatives. PCR analysis identified all the Y-derived sequence tested in the father, while the patient had them all except the AZF b,c regions which were lost. FISH analysis of the paternal Y chromosome documented Yq paracentric inversion while the patient's karyotype was 45,X/46,X,idic(Yp). No mutations were observed in MIS/MISRII genes.