SPANXA1 and Infertility: In order to evaluate a potential role of SPANX-A/D in human sperm fertility, we measured its protein levels in normal (normozoospermia) and infertile men (oligoteratoasthenozoospermia), in which the concentration of sperm cells is reduced to less than 15 × 106/ml, the sperm cell shape is abnormal and the sperm motility is diminished by over 40%.