QRICH2 and male infertility: These phenotypes are consistent with those observed in human subjects who carried the loss-of-function mutations of QRICH2. This study provides compelling evidence that the loss-of-function mutations of QRICH2 could result in MMAF and cause male infertility, and QRICH2 is a functional molecule essential for sperm flagellar development by regulating the genes associated with the accessory structure of sperm flagella.