PIWIL4 and Azoospermia: The aim of the present study was to investigate the role of HIWI2 rs508485 (T>C) and HIWI3 rs11703684 (C>T) polymorphisms and mutational analysis of TDRD5 gene in idiopathic non-obstructive azoospermia in a case-control study including 226 non-obstructive azoospermia patients and 200 fertile males.