Identification of a novel CFAP61 homozygous splicing variant associated with multiple morphological abnormalities of the flagella.

In this study, we investigated the role of a newly identified homozygous variant (c.1245 + 6T > C) in the CFAP61 gene in the development of multiple morphologically abnormal flagella (MMAF) in an infertile patient. Using exome sequencing, we identified this variant, which led to exon 12 skipping and the production of a truncated CFAP61 protein. Transmission electron microscopy analysis of the patient's spermatozoa revealed various flagellar abnormalities, including defective nuclear chromatin condensation, axoneme disorganization, and mitochondria embedded in residual cytoplasmic droplets. Despite a fertilization rate of 83.3% through ICSI, there was no successful pregnancy due to poor embryo quality.Our findings suggest a link between the identified CFAP61 variant and MMAF, indicating potential disruption in radial spokes' assembly or function crucial for normal ciliary motility. Furthermore, nearly half of the observed sperm heads displayed chromatin condensation defects, possibly contributing to the low blastulation rate. This case underscores the significance of genetic counseling and testing, particularly for couples dealing with infertility and MMAF. Early identification of such genetic variants can guide appropriate interventions and improve reproductive outcomes.