LOCALIZATION OF THE SEX-DETERMINING REGION-Y GENE IN XX MALES

Localization of the sex-determining region Y (SRY) was investigated in 2 XX males. Metaphase chromosomes from peripheral lymphocytes were stained by fluorescence in situ hybridization using DXZ1 and SRY probes. An identical hybridization signal with the SRY probe was found on an X chromosome in both cases. The karyotype of the 2 cases was 46,XX, t(X;Y)(p22.3;p11.3). It would appear that XX male is the presence of a Y-chromosome fragment transferred to the X-chromosome short arm by unequal interchange between homologous regions in the short arms of sex chromosomes.