SLC9B1 and male infertility: Besides, the defect of the Nha1-null sperm is clinically related, because NHA1 expression is either reduced or absent in patients with teratozoospermia, a male infertility condition characterized by the presence of abnormally shaped sperm in the semen (microarray data; Pubmed: GDS2697/1555142_at/SLC9B1).