SLC26A4 C.317C > A Variant: Functional Analysis and Patient-Derived Induced Pluripotent Stem Line Development.

Background: SLC26A4 is the second most common cause of hereditary hearing loss worldwide. This gene predominantly harbors pathogenic variants, including splice, nonsense, and missense. Although missense variants are relatively common, their specific effects on protein function remain unclear. Consequently, there is an urgent need to establish an in vitro system to investigate how these variants impact SLC26A4 protein function.

Methods: Genetic testing was conducted to determine the specific types of underlying genetic variants in patients. Following this, we employed plasmid transfection to evaluate the effects of the variants on both protein expression levels and the protein's subcellular localization. Thereafter, we transformed peripheral blood mononuclear cells (PBMCs) from the proband into induced pluripotent stem cells (iPSCs) through Sendai virus-mediated transduction.

Results: Genetic testing revealed that the proband carried compound heterozygous variants: SLC26A4 c.919-2A > G and c.317C > A. The c.317C > A variant markedly decreased the expression levels of SLC26A4 mRNA and its encoded protein. Additionally, it led to the protein's accumulation in the cytoplasm as aggregates. We successfully reprogrammed peripheral blood mononuclear cells from the proband into induced pluripotent stem cells (iPSCs) and verified that these iPSCs retained their pluripotency, differentiation potential, and genetic integrity.

Conclusion: These results provide important insights into the mechanisms by which SLC26A4 gene variants lead to hearing loss.