COL4A4 and focal segmental glomerulosclerosis: In 2014, Malone et al. first identified the collagen type IV alpha‐3 gene (COL4A3, MIM 120070) and collagen type IV alpha‐4 gene (COL4A4, MIM 120131) variants in a cohort of patients with a primary diagnosis of familial FSGS, suggesting that the COL4A3/COL4A4‐caused phenotypes in mature glomerular basement membrane (GBM) may cause primary FSGS 2, 6.