Expression of H-Y antigen in human males with two Y chromosomes

To determine whether the gene that controls the expression of H-Y ("male") antigen on human cells is Y-linked, we have compared the H-Y antigen level in normal males with that in three males with two Y chromosomes. Leukocytes from one XXYY and two XYY males express more H-Y antigen than leukocytes from normal XY males. We conclude that a structural gene or positive regulatory gene for H-Y antigen is on the human Y chromosome. Testing for the H-Y antigen may be of benefit in patients who have signs of masculinization but who lack an identifiable Y chromosome. Positive results for the H-Y antigen would be tentative evidence that the corresponding region of the Y chromosome was present, perhaps as part of a translocation, despite the absence of a typical Y chromosome.