Abstract
PURPOSE: To identify the disease-causing gene behind infertile couples with female infertility and abnormal fertilization. METHODS: Whole-exome sequencing and Sanger sequencing were used to identify variants in disease-causing genes in 119 infertile couples with abnormal fertilization. Molecular modeling and functional analysis were used to evaluate the pathogenic effects of the variants. RESULTS: We identified one homozygous ASTL variant and three homozygous WEE2 variants from four affected individuals. Among them, WEE2 variants c.1006(-)1007insTA (p.His337Tyrfs*24) and c.585G > C (p.Lys195Asn) have been previously reported. Structural modeling indicated that the novel ASTL variant c.643G > A (p.Glu215Lys) disrupted the hydrogen bond with Gly-213, while the novel WEE2 variant c.791C > T (p.Ala264Val) significantly decreased tyrosine 15 phosphorylation on Cdc2 and reduced pronucleus formation rate in vitro. In addition, intracytoplasmic sperm injection with assisted oocyte activation (ICSI-AOA) can prevent polyspermy in oocytes with ASTL c.643G > A (p.Glu215Lys) variant and can assist patients in delivering a girl. CONCLUSIONS: We identified novel homozygous variants in ASTL and WEE2, and functional analysis confirmed the pathogenicity of these variants. In addition, ICSI-AOA rescued the polyspermy phenotype in patients with ASTL c.643G > A (p.Glu215Lys) variant. Our findings further reveal the important role of ASTL and WEE2 in female reproduction and expand the mutational spectrum of the abnormal fertilization related genes ASTL and WEE2.