Novel WEE2 gene variants identified in patients with fertilization failure and female infertility
FERTILITY AND STERILITY
Authors: Zhao, Shuai; Chen, Tailai; Yu, Mengru; Bian, Yuehong; Cao, Yongzhi; Ning, Yunna; Su, Shizhen; Zhang, Jiangtao; Zhao, Shigang
Abstract
Objective: To determine whether variants in the WEE2 (WEE1 homolog 2, also known as WEE1B) gene, which has been known to function in the formation of pronuclei during fertilization, contribute to fertilization failure. Design: Case-control genetic study. Setting: University hospital. Patient(s): Ninety infertile women with repeated cycles of pronucleus formation failure undergoing in vitro fertilization and/or intra-cytoplasmic sperm injection treatment as well as 200 fertile control women. Intervention(s): Genomic DNA was extracted from the peripheral blood. The whole exons of WEE2 were amplified by means of polymerase chain reaction and then Sanger sequencing was performed. Main Outcome Measure(s): Variants analysis of WEE2 gene. Result(s): We identified five subjects that were subjected to homozygous or compound-heterozygous variants of WEE2: case 1 (from a consanguineous family) with homozygous frameshift variant: c.293_294insCTGAGACACCAGCCCAACC (p.Pro98Pro fsX2); case 2 with homozygous missense variant: c.1576T>G (p.Tyr526Asp); and three cases with compound-heterozygous variants: case 3: c.991C>A (p.His331Asn) and c.1304_1307delCCAA (p.Thr435Met fsX31); case 4: c.341_342 del AA (p.Lys114Asn fsX20) and c.864G>C (p.Gln288His); and case 5: c.1A>G (p.0?) and c.1261G>A (p.Gly421Arg). Besides c.1576T>G (from case 2) and c.864G>C (from case 4), which have been previously reported as rare single nucleotide polymorphisms (SNPs), the other six variants were novel and predicted by software to be deleterious. The parental genotypes of case 1 and case 2 indicated that the detected homozygous variants were inherited in an autosomal recessive mode. All of the detected variants were absent from the control cohort. Conclusion(s): Novel variants found in WEE2, which is autosomal-recessive inherited, may be related to recurrent pronucleus formation failure and female infertility. (C) 2018 by American Society for Reproductive Medicine.
Homozygous Mutations in WEE2 Cause Fertilization Failure and Female Infertility
AMERICAN JOURNAL OF HUMAN GENETICS
Authors: Sang, Qing; Li, Bin; Kuang, Yanping; Wang, Xueqian; Zhang, Zhihua; Chen, Biaobang; Wu, Ling; Lyu, Qifeng; Fu, Yonglun; Yan, Zheng; Mao, Xiaoyan; Xu, Yao; Mu, Jian; Li, Qiaoli; Jin, Li; He, Lin; Wang, Lei
Abstract
Fertilization is a fundamental process of development and is a prerequisite for successful human reproduction. In mice, although several receptor proteins have been shown to play important roles in the process of fertilization, only three genes have been shown to cause fertilization failure and infertility when deleted in vivo. In clinical practice, some infertility case subjects suffer from recurrent failure of in vitro fertilization and intracytoplasmic sperm injection attempts due to fertilization failure, but the genetic basis of fertilization failure in humans remains largely unknown. Wee2 is a key oocyte-specific kinase involved in the control of meiotic arrest in mice, but WEE2 has not been associated with any diseases in humans. In this study, we identified homozygous mutations in WEE2 that are responsible for fertilization failure in humans. All four independent affected individuals had homozygous loss-of-function missense mutations or homozygous frameshift protein-truncating mutations, and the phenotype of fertilization failure was shown to follow a Mendelian recessive inheritance pattern. All four mutations significantly decreased the amount of WEE2 protein in vitro and in affected individuals' oocytes in vivo, and they all led to abnormal serine phosphorylation of WEE2 and reduced tyrosine 15 phosphorylation of Cdc2 in vitro. In addition, injection of WEE2 cRNA into affected individuals' oocytes rescued the fertilization failure phenotype and led to the formation of blastocysts in vitro. This work presents a novel gene responsible for human fertilization failure and has implications for future therapeutic treatments for infertility cases.