P-284 DLGAP5 mutations cause female infertility and oocyte maturation defects with abnormal meiotic process via regulating PI3K-AKT pathway

Study question Are discs large-associated protein 5 (DLGAP5) variants associated with human oocyte maturation abnormality and female infertility? Summary answer Mutations in DLGAP5 cause human female infertility by inducing oocyte maturation defects via regulating PI3K-AKT pathway. What is known already Various forms of oocyte maturation defects have been reported, and an increasing number of pathogenic genes have been identified. At present, the known genetic causes of abnormal oocyte development can only account for a minority of female infertility, and the candidate genes responsible for oocyte maturation defects remain largely under investigation. This study aimed to identify novel genetic causes responsible for human oocyte maturation abnormality and female infertility. Study design, size, duration Whole-exome sequencing (WES) analyses were performed on infertile patients with abnormal oocyte development to identify novel genetic causes. Participants/materials, setting, methods We performed WES on infertile female patients and analyzed the possible impact of the variants of candidate genes on protein expression. And knockout mouse was established to investigate the role of candidate genes in mouse oocyte development. Main results and the role of chance Three infertile female patients from two families with oocyte maturation lag were identified to carry a homozygous nonsense mutation c.1101C>G, p.Tyr367* in DLGAP5, which is first reported as candidate pathological gene for human infertility. This mutation caused severe impairment in the DLGAP5 expression in the affected oocytes, leading to abnormal embryo development. Further cell experiments elucidated that DLGAP5 participates in cell division, and its depletion or mutation can induce G2/M arrest. The depletion of DLGAP5 in human oocytes by microinjection of siRNAs resulted in abnormal spindles and reduced germinal vesicle breakdown and polar body 1 extrusion rate. In addition, a similar phenotype of abnormal oocyte development was observed in Dlgap5-deficient mouse oocytes, which could be rescued by DLGAP5 cRNA microinjection. Furthermore, Dlgap5 knockout altered expression of genes involving in meiosis process and deactivated PI3K-AKT signaling pathway in oocytes. And PI3K-AKT activators facilitated the oocyte maturation resumption in Dlgap5-deficient mice. Limitations, reasons for caution The mutation in DLGAP5 was identified in only three patients from two families. The sample size was too limited, and more comprehensive gene screening is needed to confirm our results. Further screening and exploration are required to comprehend the penetrance of the candidate pathogenicity-related genes comprehensively. Wider implications of the findings Our study expands the current spectrum of pathogenic genes responsible for abnormal oocyte maturation and provides crucial insights into clinical consultation, genetic diagnosis, and treatment strategies among infertile patients. Trial registration number No