COL4A3 and focal segmental glomerulosclerosis: However, patients with type IV collagen-related nephropathy carrying heterozygous mutations in COL4A3 and COL4A4 show broad and diverse clinical phenotypes, and the disease spectrum varies from TBMN with microscopic hematuria or TBMN and/or FSGS with hematuria and varying degrees of proteinuria to ARAS with progressive renal failure [9].