To obtain a gene which might be useful for identifying a gene which causes spermatogenetic diseases and for knowing mutation by including a base sequence coding for human male dominant expression antigen-2 (human MEA-2) having a specific amino acid sequence.

This gene contains a base sequence coding for human MEA-2 having the amino acid sequence shown by formula I or a sequence complementary to the sequence. This gene has the base sequence shown by formula II, and consists of genomic DNA, cDNA or RNA. It is preferable to detect diseases such as spermatogenesis caused by human MEA-2 gene by detecting mutation in the base sequence shown by formula II, and to carry out the detection by the polymerase chain reaction or to select a sequence into which mutation site is inserted as a primer sequence in the base sequence shown by formula II.