CFAP251 Deficiency Induces Male Infertility and PCD-like Ciliary Defects by Disrupting TUBB4B and SLC25A4 Recruitment in Humans and Mice

Mutations in the Cfap251 gene have been identified as causative for morphology and motility abnormalities in spermatozoa of infertile males, manifesting as multiple morphological abnormalities of the sperm flagella (MMAF).However, the mechanism underlying CFAP251-associated MMAF remains poorly understood, and the role of CFAP251 deficiency in PCD remains unclear.This study aimed to elucidate the pathogenic mechanism linking CFAP251 deficiency to human male infertility and to determine whether CFAP251 plays an active role in both flagella and cilia across species.A Cfap251 knockout mouse line was generated on a C57Bl/6J strain.CFAP251 mutations were identified by whole-exome sequencing on probands from Han Chinese families with primary infertility and MMAF.The Cfap251 knockout mouse model replicated the MMAF and male infertility phenotypes observed in humans for the first time.Moreover, the Cfap251 knockout mouse and one patient showed PCD-like symptoms, including tinnitus, seasonal cough, and radiological findings of coarsened lung markings and solitary pulmonary bulla associated with chronic bronchitic inflammation.Mechanistically, CFAP251 was confirmed to interact with TUBB4B, and its disruption led to the downregulation of TUBB4B, impairing spermiogenesis and ciliary function.Furthermore, CFAP251 was found to interact with the mitochondrial protein SLC25A4, suggesting a role in regulating energy transport.Favorable outcomes following ICSI were observed, with the successful birth of healthy offspring in four patients caused by CFAP251 variants.These included two cases with two novel homozygous splice-altering variants (c.1535+1G>C and c.1269+2T>C) and two previously reported MMAF cases.Our findings highlight the underlying risk of male infertility and PCD-like ciliary defects associated with CFAP251 and provide a valuable reference for personalized genetic counselling and clinical treatment of affected individuals.