A novel mouse model for X-linked Alport syndrome induced by splicing mutation in the Col4a5 gene.

Alport syndrome is a hereditary kidney disease with significant variations in onset and prognosis. While 80-85% of cases are due to pathogenic variants in the COL4A5 gene, there is a notable lack of mouse models with Col4a5 mutations for basic research. Our research presents an 8-year-old child with Alport syndrome, exhibiting facial edema and abnormal urine. Next-generation sequencing revealed a c.1517-1G > T mutation in the intron sequence of the COL4A5 gene. Minigene experiments confirmed that this intronic mutation affects mRNA splicing. Using the CRISPR/Cas9 system, we developed a Col4a5-c.1517-1G > T mutant mouse model. Col4α5-deficient mice exhibited growth retardation and reduced lifespan. Renal function analysis indicated progressive deterioration, with high levels of BUN and creatinine. Histological and ultrastructural analyses revealed abnormalities such as mesangial sclerosis, interstitial fibrosis and severe irregularity in membrane thickness. Additionally, significant immune cell infiltration was observed in the renal interstitium. This mouse model provides a valuable tool for studying the role of immune cells in the pathogenesis and treatment of XLAS. It is also the first reported X-linked Alport syndrome mouse model caused by a splicing mutation.