Expression of two G-6-PD genes in an XX phenotypic male

The glucose-6-phosphate dehydrogenase (G-6-PD) gene is located on the X-chromosome. Normal males have a single gene and produce a single G-6-PD type, while normal XX females may be heterozygotes for two different G-6-PD genes. We report the case of a phenotypic male who was found to be heterozygous for two G-6-PD enzymes. Cytogenetic analysis showed that he was a 46,XX male.