BRD2 and Azoospermia: Given the difficulty in obtaining semen samples from asymptomatic patients, serum follicle-stimulating hormone (FSH) was used as a surrogate marker of spermatogenic function because previous studies demonstrated that FSH level in adults seems to be correlated with spermatogenetic activity [14, 15] and to be a predictive marker for the sperm retrieval rate in patients with non-obstructive azoospermia [16, 17], although exact role of FSH remains unclear.