PIWIL4 and Azoospermia: Considering the functional and physiological importance of HIWI and TDRD genes in male fertility and the results of our previous pilot study concerning the association between rs508485 and azoospermia21, the aim of the present study was to analyze the association between HIWI2 rs508485 (T>C) and HIWI3 rs11703684 (C>T) polymorphisms with the risk of azoospermia in a larger sample of Iranian infertile men with idiopathic non-obstructive azoospermia.