Non-obstructive azoospermia (NOA) is the most severe form of male infertility and typically incurable. Defining the genetic basis of NOA has proven chal lenging, and the most advanced classification of NOA subforms is not based on genetics, but simple description of testis histology. In this study, we exome sequenced over 1000 clinically diagnosed NOA cases and identified a plausible recessive Mendelian cause i...