A Novel Mutation of <i>DAX-1</i> Associated with Secretory Azoospermia

Secretory azoospermia is a severe form of male infertility caused by unknown factors. DAX-1 is predominantly expressed in mammalian reproductive tissues and plays an important role in spermatogenesis because Dax-1 knockout male mice show spermatogenesis defects. To examine whether DAX-1 is involved in the pathogenesis of secretory azoospermia in humans, we sequenced all of the exons of DAX-1 in 776 patients diagnosed with secretory azoospermia and 709 proven fertile men. A number of coding mutations unique to the patient group, including two synonymous mutations and six missense mutations, were identified. Of the missense mutations, our functional assay demonstrated that the V385L mutation caused the reduced functioning of DAX-1. This novel mutation (p. V385L) of DAX-1 is the first to be identified in association with secretory azoospermia, thereby highlighting the important role of DAX-1 in spermatogenesis.