That HSFY is functional and required for spermatogenesis is evident from the observations in four infertile males with a large 768 kb deletion around the P4 palindrome at the proximal end of the AZFb interval that resulted in loss of both HSFY1 and HSFY2, and six non-coding transcription units FAM41AY2, NCRNA00230B, TTTY9A, TTTY9B, NCRNA00185 and TTTY14 [98]. The gene discussed is HSFY1; the disease is Infertility.