USP9Y and Azoospermia: Early reports have suggested a role for USP9Y in spermatogenic failure associated with azoospermia and male infertility, where point mutations in USP9Y were found in males with spermatogenic failure and were absent in their fertile male siblings or in the control fertile group (Brown et al., 1998; Hall et al., 2003; Sun et al., 1999), however recent papers have challenged this view (Krausz et al., 2006; Luddi et al., 2009).