Novel <i>DNAH1</i> variants in Chinese males with MMAF-associated asthenoteratozoospermia

Asthenoteratozoospermia is a major contributor to male infertility, with multiple morphological abnormalities of the flagellum (MMAF) representing a genetically heterogeneous disorder characterized by structural defects in sperm flagella. To identify the genetic determinants underlying MMAF-associated infertility, we conducted a comprehensive and systematic investigation involving Chinese infertile couples exhibiting the MMAF phenotype and undergoing assisted reproductive technology (ART). Our integrated approach combined whole-exome sequencing (WES) with Sanger sequencing for variant validation, complemented by scanning and transmission electron microscopy (SEM/TEM) to elucidate ultrastructural features. Molecular analyses included quantitative real-time PCR (qRT-PCR) and immunofluorescence (IF) to evaluate both transcriptional and translational alterations. We identified novel variants in six loci of dynein axonemal heavy chain 1 (<i>DNAH1</i>), including both missense and frameshift variants, across three unrelated families. Affected spermatozoa demonstrated characteristic morphological and ultrastructural abnormalities, while qRT-PCR and IF analyses revealed altered expression patterns of <i>DNAH1</i>. Personalized ART strategies enabled successful pregnancies in individuals harboring <i>DNAH1</i> variants. While the limited sample size reflects the rarity of this genetic disorder, functional validation beyond expression analysis and structural prediction remains limited. Larger cohorts and in-depth biochemical assays will be required to generalize the findings. Nonetheless, our findings provide important insights into the genetic mechanisms of MMAF and its clinical management.