Genetic architecture and phenotypic diversity of oocyte and early embryo competence defects in female infertility.

Oocyte and early embryo competence defects (OECD) represent a recently recognized cause of female infertility with the application of assisted reproductive technology, characterized by impaired oocyte or early embryo development. To investigate the genetic landscape and subtypes of OECD, we performed whole-exome sequencing on 2,140 patients, classifying them into six distinct subtypes. We identified 183 pathogenic/likely pathogenic variants across 28 established genes. Notably, distinct genetic profiles and diagnostic rates emerged across subtypes, with a rate of 53% in the Empty Follicle subtype. Additionally, we identified and validated two potentially causative genes, MLH3 and CENPH. Gene burden analysis, using 2,424 fertile controls, suggested nine potential previously unreported associated genes and offered biological insights into the underlying pathogenic mechanisms of OECD. Collectively, these genetic findings accounted for 12.8-23.1% of OECD cases. This study delineates the genetic architecture of OECD, offering insights that may inform the development of diagnostic genetic screenings and provide a reference for standardized subtyping of patients with OECD.