ZRSR2P1 and Azoospermia: Zrsr1 is a U2AF35-like splicing factor which recognizes the 3' splice site during spliceosome assembly, and the Zrsr1 mutant mice containing truncating mutations within its RRM exhibits the abundant intron retention events in genes associated with spermatogenesis, and germ cell apoptosis, azoospermia and male sterility 77.