Sex-Linkage of Glucose-6-Phosphate Dehydrogenase in the Horse and Donkey

Distinctly different electrophoretic patterns of red cell glucose-6-phosphate dehydrogenase were resolved from the hemolyzates of horse and donkey erythrocytes. Examination of their reciprocal hybrids, mules and hinnies, showed that the red cells of female mules and female hinnies contain both horse and donkey G-6-PD; the male mule with an X chromosome from its horse mother contained pure horse G-6-PD, whereas the male hinny with the donkey X chromosome contained pure donkey G-6-PD. These findings on the male reciprocal hybrids suggest X-linkage.