NR5A1 and Azoospermia: The expression of key protein StAR that plays an essential role in testosterone synthesis was reported to be regulated by steroidogenic factor-1 (SF-1, NR5A1, Ad4BP) [52], which is a nuclear receptor regulatory gene involved in steroidogenesis, adrenal/gonadal development and the reproductive axis [53]. The investigation into human infertility cases from Bashamboo and co-workers found that the men who harbored NR5A1 changes had lower levels of testosterone and more fateful infertility such as azoospermia and oligozoospermia [54].