Purpose: To investigate the genetic cause of nonobstructive azoospermia (NOA). 7 Methods: We performed whole exome sequencing (WES) on the proband who had three 8 relatives suffering from NOA. We used a list of candidate genes which have high expression 9 level in testis and their mutations have been reported in NOA. Sanger sequencing verified the 10 identified variant and its structural and functional consequence was evaluated by protein three11 dimensional (3D) structure prediction and protein-ligand docking. 12 Results: WES revealed a novel splice-acceptor mutation (c.1832-2A>T) in helicase for meiosis 13 1 (HFM1) gene, which co-segregated with the NOA in this family. 3D structural models were 14 generated and verified. Molecular docking indicated that the c.1832-2A>T mutation affects not 15 only the ADP binding residues but also the hydrogen bonds interactions. The ADP binding site 16 will be lost in the mutant protein which potentially causing defective crossover and synapsis. 17 Conclusion: We report that the c.1832-2A>T mutation is the likely cause of NOA in the family 18 studied. Regarding that many reported NOA genes are involved in the formation of crossovers 19 and synapsis and have critical roles in the production of germ cells, we suggest that such genes 20 should be considered for screening of infertility among large cohorts of infertile individuals.

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