Mice with disruption of the gene Slc12a2 encoding both NKCC1 splice variants (NKCC1a and NKCCb) are viable, but suffer from deafness, pain perception, and male infertility (Randall et al., 1997; Delpire et al., 1999; Delpire and Mount, 2002). This evidence concerns the gene SLC12A2 and male infertility.