Abstract

STUDY QUESTIONDoes DNAH14 deficiency impair sperm flagellar integrity and contribute to male infertility?SUMMARY ANSWERLoss of DNAH14 leads to disrupted sperm annulus positioning, defective mitochondrial assembly, reduced sperm motility, and impaired male fertility in both humans and mice.WHAT IS KNOWN ALREADYPathogenic variants in several axonemal dynein heavy chain (DNAH) genes have been implicated in male infertility and primary ciliary dyskinesia. DNAH14 remains the only member whose roles are undefined.STUDY DESIGN, SIZE, DURATIONGenetic analysis was performed on two unrelated Han Chinese infertile men. Functional studies were carried out in a CRISPR-Cas9 Dnah14 knockout (KO) mouse model, with phenotyping of males and their offspring.PARTICIPANTS/MATERIALS, SETTING, METHODSWhole-exome sequencing was applied to patient samples. Dnah14 KO mice were generated to assess reproductive phenotypes. Sperm morphology and motility were analyzed using Papanicolaou staining, scanning electron microscopy (SEM), transmission electron microscopy (TEM), immunofluorescence staining, and computer-assisted sperm analysis (CASA). Intracytoplasmic sperm injection (ICSI) was performed in both patients and KO mice, and offspring survival and growth were monitored.MAIN RESULTS AND THE ROLE OF CHANCEBiallelic DNAH14 variants were identified in two men with asthenoteratozoospermia. Patient HX-042 carried compound heterozygous variants c.1055T>C and c.9788T>C, whereas Patient HX-137 harbored compound heterozygous variants c.10434G>T and c.12512A>G. In both cases, sperm exhibited markedly reduced motility, disrupted annulus positioning and mitochondrial disorganization. DNAH14 was specifically localized to the midpiece of both human and mouse sperm. Dnah14 KO mice exhibited subfertility, characterized by reduced sperm motility, sperm mitochondrial sheath anomaly, annulus mislocalization, and