Malcher et al. (2013) found that spaca4 is one of the most significantly downregulated (fold change = 5.71) genes in patients with idiopathic non-obstructive azoospermia compared with those in control patients. This indicates that spaca4 may serve as a potential biomarker of azoospermia and as a molecular indicator that could determine the particular stage of impaired spermatogenesis. Here, SPACA4 is linked to Azoospermia.