DNAI3 and Azoospermia: For example, deletion of SPINK2, an azoospermia-associated gene, caused oligo-teratozoospermia in mice (30), and knockout of Wdr63, a gene mutated in both multiple morphological abnormalities of the sperm flagella and NOA patients, led to infertility with decreased sperm number and abnormal flagellar morphology in mice (31).