The higher level of the protein in the seminal plasma of men with oligozoospermia and azoospermia could be attributed to a diminution in the number of MSMB molecules bound to the spermatozoa due to the absence or low concentration of binding sites for MSMB on the sperm surface which consequently increases the free, unattached protein levels in seminal plasma. The gene discussed is MSMB; the disease is Azoospermia.