Reproductive and Genetic Hospital of CITIC-Xiangya, Changsha, China.
Institute of Reproductive and Stem Cell Engineering, School of Basic Medicine, Central South University, Changsha, China.
Genet Med. 2019 Feb;21(2):431-440. doi: 10.1038/s41436-018-0064-y. Epub 2018 Jun 12.
The oocyte-borne genetic causes leading to fertilization failure are largely unknown. We aimed to identify novel human pathogenic variants (PV) and genes causing fertilization failure.
We performed exome sequencing for a consanguineous family with a recessive inheritance pattern of female infertility characterized by oocytes with a thin zona pellucida (ZP) and fertilization failure in routine in vitro fertilization. Subsequent PV screening of ZP2 was performed in additional eight unrelated infertile women whose oocytes exhibited abnormal ZP and similar fertilization failure. Expression of ZP proteins was assessed in mutant oocytes by immunostaining, and functional studies of the wild-type and mutant proteins were carried out in CHO-K1 cells.
Two homozygous s PV (c.1695-2A>G, and c.1691_1694dup (p.C566Wfs*5), respectively) of ZP2 were identified in the affected women from two unrelated consanguineous families. All oocytes carrying PV were surrounded by a thin ZP that was defective for sperm-binding. Immunostaining indicated a lack of ZP2 protein in the thin ZP. Studies in CHO cells showed that both PV resulted in a truncated ZP2 protein, which might be intracellularly sequestered and prematurely interacted with other ZP proteins.
We identified loss-of-function PV of ZP2 causing a structurally abnormal and dysfunctional ZP, resulting in fertilization failure and female infertility.
导致受精失败的卵母细胞遗传病因在很大程度上尚不清楚。我们旨在鉴定导致受精失败的新型人类致病性变异（PV）和基因。
我们对一个具有隐性遗传模式的常染色体隐性遗传家族进行了外显子组测序，该家族的女性不孕特征为卵母细胞透明带（ZP）薄，常规体外受精受精失败。随后在另外 8 名具有异常 ZP 和类似受精失败的非相关不孕妇女中进行了 ZP2 的 PV 筛查。通过免疫染色评估突变卵母细胞中 ZP 蛋白的表达，并在 CHO-K1 细胞中对野生型和突变蛋白进行功能研究。
在两个不相关的近亲家庭中，受影响的女性分别发现了 ZP2 的两个纯合 sPV（c.1695-2A>G 和 c.1691_1694dup（p.C566Wfs*5））。携带 PV 的所有卵母细胞均被薄的 ZP 包围，该 ZP 不利于精子结合。免疫染色表明，薄的 ZP 中缺乏 ZP2 蛋白。CHO 细胞研究表明，两种 PV 均导致 ZP2 蛋白截短，这可能导致其在细胞内被隔离并过早与其他 ZP 蛋白相互作用。
我们鉴定出 ZP2 的功能丧失性 PV，导致结构异常和功能失调的 ZP，从而导致受精失败和女性不孕。
