Mutation analysis of ZP1, ZP2, ZP3 and ZP4 genes in 152 Han Chinese samples with ovarian endometriosis

Endometriosis is characterized by the ectopic implant of endometrial tissue outside the uterine cavity and found in ˜35–50% of subfertile women. Previous studies have found that endometriosis had frequent defects in zona pellucida (ZP), and mutations in ZP genes could lead to ZP defects, raising the possibility that mutations in ZP genes might exist in endometriosis. We analyzed a total of 152 Han Chinese samples with ovarian endometriosis for the presence of mutations in the ZP1, ZP2, ZP3 and ZP4 genes. Two novel nonsynonymous ZP4 mutations were identified in three out of 152 (2.0%) samples: a p.M1?/(c.3 G > C) mutation in a 27- and 35-year-old sample, respectively, and a p.A433 V (c.1298C > T) mutation in a 31-year-old patient. No mutations were detected in ZP1, ZP2 or ZP3 genes; furthermore, no mutations in ZP genes were identified in 85 female control samples without endometriosis. The p.M1?/(c.3 G > C) mutation could lead to the usage of a downstream translation initiation site, while the evolutionary conservation and protein structural modeling analyses suggested that the p.A433 V mutation might be functionally important. However, there were strikingly different fertility outcomes among the three samples with ZP4 mutations: the p.A433V-mutated sample had no problem in fertility; while the p.M1?-mutated samples presented with paradoxical effects on fertility: the 35-year-old patient had a child while the 27-year-old patient was infertile, who underwent two spontaneous abortions and an implantation failure after IVF treatment. These results suggested that the potential role of ZP4 mutations on human fertility might be more complex than we thought, and other genetic and environment factors might play a role. In conclusion, we identified two novel mutations in the ZP4 gene in 2.0% of Han Chinese patients with ovarian endometriosis for the first time, our results suggested that mutations in ZP4, but not ZP1, ZP2 and ZP3, might play active roles in the pathogenesis of ovarian endometriosis, despite the mutation-carriers present with complex fertility outcomes.