The axoneme of the human sperm has a very similar ultrastruc-ture to motile cilia,the “9 + 2” structure,comprising nine periph-eral double microtubules plus two central pairs (Nicastro et al.,2006;Ishikawa,2017).A proteomics analysis identified more than 700 proteins exclusively in the sperm tail,and abnormal expression of related genes can cause male infertility with multiple morpho-logical abnormalities of flagella (MMAF),including absent,coiled,short,and irregular-caliber flagella (Baker et al.,2013;Coutton et al.,2015).Whole-exome sequencing (WES) results identified numerous pathogenic genes associated with MMAF,demonstrating the genetic heterogeneity of MMAF (Yang et al.,2015;Wang et al.,2020).However,these variants only explain approximately two-thirds of all MMAF cases,indicating that other genetic causes and pathogenic mechanisms of MMAF need to be investigated.