Primary azoospermia factor C duplication associated with spermatogenic impariment: a case-control study based on Y-chromosome haplogrouping in a Han Chinese population.

. Meanwhile, the b2/b3 duplication may be fixed on a yet-unidentified subbranch of Y-hg Cα2* without significantly deleterious effect on spermatogenesis. Our findings provide evidence that the difference in the Y-hg composition may cause the discrepancy on the association of AZFc duplication with spermatogenic failure among the studied populations.