Objective: To search for the possible pathogenic genes for multiple morphological anomalies of sperm flagella (MMAF).
Methods: We performed whole exome sequencing (WES) of a typical case of MMAF and analyzed its possible pathogenic genes. We examined the semen sample from the patient and identified the ultrastructural characteristics of the sperm flagella under the scanning electron and transmission electron microscopes, and analyzed the expression pattern of cilia and flagela-associated protein 65 (CFAP65) in spermatogenesis by immunofluorescence assay.
Results: The MMAF patient was found with a homozygous pathogenic mutation of the CFAP65 gene c.2675G>A(p.Trp892*). Scanning electron microscopy showed that the sperm of the patient had typical characteristics of MMAF, that is, without tails or with folded tails, curly tails, short tails or irregular tails. Transmission electron microscopy revealed the loss and disorder of the "9+2" structure in the sperm flagellum, with abnormal assembly of the fibrous sheath, accompanied by loss of central microtubules and dynamin arms. Cellular immunofluorescence assay suggested that the CFAP65 gene was expressed at all levels of mouse germ cells.
Conclusions: The CFAP65 gene is involved in the assembly of the sperm flagellum structure, and its mutation can cause the phenotype of MMAF, leading to male infertility.
Keywords: cilia and flagella-associated protein 65; gene mutation; male infertility; multiple morphological abnormalities of sperm flagella; whole-exome sequencing.