Exome sequencing identifying additional QRICH2 mutations in oligo-astheno-teratozoospermia and asthenospermia patients

Abstract

Our recent study has shown that loss-of -function of QRICH2, a testis specific expressed gene, is associated with male infertility with multiple morphological abnormalities of the flagella (MMAF), the current study aim to determine whether QRICH2 mutations were associated with other more common forms of male infertility, such as oligo-astheno-teratozoospermia and asthenospermia Experimental study recruited from male infertility clinic and human samples of case and control were collected. 84 cases of male infertility patients were recruited. WES was performed for all subjects. All identified variants were confirmed by Sanger sequencing. Immunostaining result was used to determine the specific localization of QRICH2 in human sperm. Western blot were used to detect the expression of QRICH2 in oligo-astheno-teratozoospermia . Co-Immunoprecipitation (Co-IP) with QRICH2 antibody in human testis and proteomics analysis were conducted to identify the binding partner. IVF/ICSI outcome were followed to determine whether the mutation of QRICH2 have effect on the normal development of offspring. We identified five unrelated patients (5/84, 5.9%) with homozygous and compound heterozygous mutations in the QRICH2 gene, which is specifically expressed in human and mouse testis. Three of the samples harbor a recurrent deletion, (g.17:74288566_74288568del,c.1742_1744del,p.581_582del) .None of these mutations were reported in control sequence databases. 4 of mutation is located in the SNC-N domain, while one mutation is located in the Glutamine rich domain. Co-IP result indicated that mitochondrial proteins, such as VDAC1 is associated with QRICH2 . Western blot result shows that QRICH2 expression is -down-regulated in patients. And IVF/ICSI outcome analysis indicates that normal offspring development could be observed in the patients. Compared with other reported genes associated with male infertility , high frequency of QRICH2 mutations were detected with WES. QRICH2 is important for sperm motility. The mutation of QRICH2 gene, especially high frequency mutations of SMC_N domain are likely responsible for the phenotypes of both oligo-astheno-teratozoospermia and asthenospermia.