Biallelic Mutations in CFAP43 and CFAP44 Cause Male Infertility with Multiple Morphological Abnormalities of the Sperm Flagella

Abstract

Sperm motility is vital to human reproduction. Malformations of sperm flagella can cause male infertility. Men with multiple morphological abnormalities of the flagella (MMAF) have abnormal spermatozoa with absent, short, coiled, bent, and/or irregular-caliber flagella, which impair sperm motility. The known human MMAF-associated genes, such as DNAH1, only account for fewer than 45% of affected individuals. Pathogenic mechanisms in the genetically unexplained MMAF remain to be elucidated. Here, we conducted genetic analyses by using whole-exome sequencing and genome-wide comparative genomic hybridization microarrays in a multi-center cohort of 30 Han Chinese men affected by MMAF. Among them, 12 subjects could not be genetically explained by any known MMAFassociated genes. Intriguingly, we identified compound-heterozygous mutations in CFAP43 in three subjects and a homozygous frameshift mutation in CFAP44 in one subject. All of these recessive mutations were parentally inherited from heterozygous carriers but were absent in 984 individuals from three Han Chinese control populations. CFAP43 and CFAP44, encoding two cilia-and flagella-associated proteins (CFAPs), are specifically or preferentially expressed in the testis. Using CRISPR/Cas9 technology, we generated two knockout models each deficient in mouse ortholog Cfap43 or Cfap44. Notably, both Cfap43-and Cfap44-deficient male mice presented with MMAF phenotypes, whereas the corresponding female mice were fertile. Our experimental observations on human subjects and animal models strongly suggest that biallelic mutations in either CFAP43 or CFAP44 can cause sperm flagellar abnormalities and impair sperm motility. Further investigations on other CFAP-encoding genes in more genetically unexplained MMAF-affected individuals could uncover novel mechanisms underlying sperm flagellar formation.

A novel homozygous CFAP65 mutation in humans causes male infertility with multiple morphological abnormalities of the sperm flagella

“…One is that the disruption of the CFAP65 gene caused by Rose‐comb mutation in chickens can lead to impaired sperm motility in male homozygotes . Another research detected a different homozygous nonsense mutation in CFAP65 (c.5341G>T; [p.Glu1781*]) in an infertile male with MMAF . Here, we identified the negative effect of the p.Trp892* mutation on CFAP65 expression and the sperm flagellar development.…”

“…Since 2014, when MMAF was defined, studies have shown that mutations in genes associated with sperm flagellum development may lead to MMAF . Here, another candidate gene, CFAP65 , was identified in an infertile male with MMAF by WES.…”

“…The genetic basis of male infertility is still a work in progress, more than 4000 genes are expressed in germ cells during sperm production, and variations in these genes may hamper spermatogenesis . Recent studies of families with positive history related to male infertility have reported that mutations in cilia‐related genes are responsible for MMAF (eg, DNAH1 , CFAP43 , CFAP44 , CFAP69 , CFAP251 , QRICH2 , AK7 , CEP135 , FSIP2 , SPEF2 , TTC21A , ARMC2 , AKAP4 , CCDC39 ) . However, the known genetic defects can only explain ~60% of the individuals affected by MMAF …”

Patients with multiple morphological abnormalities of the sperm flagella harbouring CFAP44 or CFAP43 mutations have a good pregnancy outcome following intracytoplasmic sperm injection

“…Multiple studies have indicated that biallelic mutations in DNAH1, CFAP43 and CFAP44, which occur with a frequency that is independent of genetic origin, cause the majority of MMAF cases (Amiri-Yekta et al, 2016;Ben Khelifa et al, 2014;Sha et al, 2018;Sha, Yang, et al, 2017;Tang et al, 2017;Wang et al, 2017). Multiple studies have indicated that biallelic mutations in DNAH1, CFAP43 and CFAP44, which occur with a frequency that is independent of genetic origin, cause the majority of MMAF cases (Amiri-Yekta et al, 2016;Ben Khelifa et al, 2014;Sha et al, 2018;Sha, Yang, et al, 2017;Tang et al, 2017;Wang et al, 2017).…”

Assessment of Human Sperm Cells Morphological Parameters

“…Multiple morphological abnormalities in the same patient's spermatozoa tail structure and ultrastructure which impair motility can show the mutation of some genes (DNAH1, DNAJB13, CFAP43 and CFAP44) [70][71][72][73].…”