Sperm Tail would Cause of Fertilization Failure due to the Genetic Problem

they suggested that human CatSper mutations with infertility phenotype are quite rare because the patient must have homozygous mutations (the identical mutation in both alleles) for CatSper-less phenotype. Therefore, they only have seen two patients like this. The patient from PNAS paper had homozygous microdeletion in chromosome 15 which also affected CatSper2 gene, two of his brothers had the same deletions and all three brothers were infertile. They only examined sperm cells from one of the brothers. The men with affected CatSper, just like CatSper knockout mice and they theoretically should have normal sperm count and normal motility. However, sperm hyperactivation will be affected. Their patients had severe oligo-therato-asthenozoospermia, but probably due to the removal of other genes, adjacent to CatSper 2 locus. They never ever seen fertile men with CatSper locuses affected on both alleles. If only one is affected, the other one will rescue the phenotype. Heterozygous mice are perfectly normal, hence they assumed that humans should have similar trend. Additionally, three brothers indeed have very similar genetics with identical microdeletion [2].