H-Y antigen is a male tissue specific antigen. Originally thought to trigger the formation of testes (via loci, an autosomal gene that generates the antigen and one that generates the receptor) it is now known that it does not trigger the formation of testes but may be activated by the formation of testes.
There are several antigens which qualify as H-Y as defined by rejection of male skin grafts in female hosts or detected by cytotoxic T cells or antibodies. One H-Y, secreted by the testis, defined by antibodies, is identical to Müllerian-inhibiting substance (AMH gene). Another H-Y, minor histocompatibility antigen, seemed to be encoded in the SMCY gene (acronym for 'selected mouse cDNA on Y'), later identified as an 11-residue peptide from the Lysine-Specific Demethylase 5D protein (KDM5D gene) presented by HLA-B7. A third example is MEA1.