Pathogenesis of acephalic spermatozoa syndrome caused by PMFBP1 mutation

Background Acephalic spermatozoa syndrome is a rare but severe type of teratozoospermia. The familial trait of Acephalic spermatozoa syndrome suggests that genetic factors play an important role. However, the known mutations only account for some Acephalic spermatozoa syndrome patients, and more studies are required to elucidate its pathogenesis. To elucidate the pathogenesis of acephalic spermatozoa syndrome caused by PMFBP1 mutation. We utilized Sanger sequencing to detect mutations in the genes SUN5 and PMFBP1 in a patient diagnosed with acephalic spermatozoa syndrome. Western blot analysis and immunofluorescence were employed to determine the presence and distribution of PMFBP1 in sperm. Additionally, a mutant form of PMFBP1 was generated, and its mRNA expression level was subsequently confirmed through in vitro studies. Results We identified a homozygous splice site mutation (NM_031293.2, c.2089-1G > T) in PMFBP1. Western blotting and immunofluorescence analyses revealed that this splice site mutation resulted in the absence of PMFBP1 protein expression in the patient's sperm cells. We generated an in vitro model carrying the splice site mutation in PMFBP1 and confirmed through RT‒PCR and Sanger sequencing that it led to a deletion of 4 base pairs from exon 15. Conclusion A homozygous splice site mutation results in the deletion of 4 bp from exon 15 of PMFBP1, thereby affecting the expression of the PMFBP1 protein. The absence of PMFBP1 protein expression can lead to Acephalic spermatozoa syndrome. This finding elucidates the underlying cause of Acephalic spermatozoa syndrome associated with this specific mutation (NM_031293.2, c.2089-1G > T) in PMFBP1.