ABSTRACT
Background
Severe asthenozoospermia, particularly when associated with multiple morphological abnormalities of the flagella (MMAF), represents a genetically influenced disorder, although the precise pathogenic mechanisms remain incompletely characterized.
Methods
In this study, whole-exome sequencing (WES) was performed for 44 asthenoteratozoospermia patients, and 11 pathogenic genes were detected in 20 of them (45.5%). Our investigation focused on CFAP74 variants identified in two unrelated patients: a homozygous c.3532G>A mutation in Patient P43 and novel compound heterozygous variants (c.2452C>T and c.3044T>C), first reported in this study, in Patient P24.
Results
Ultrastructural analyses using scanning and transmission electron microscopy revealed characteristic flagellar defects, including a thinner midpiece, disorganized mitochondrial sheath arrangement and axonemal structural abnormalities. Immunofluorescence analysis demonstrated that CFAP74 localized at the entire flagella of control and proband spermatozoa, indicating these missense variants do not disrupt protein expression or subcellular location. Notably, the P24 couple experienced three failed intracytoplasmic sperm injection (ICSI) attempts prior to achieving successful pregnancy through donor sperm by in vitro fertilization (IVF), highlighting the clinical implications of CFAP74-related fertility impairments.
Conclusion
This study expands the mutational spectrum of CFAP74 and further supports the causality between CFAP74 mutations and male infertility.