Pathogenic mutations in the COL4A3 or COL4A4 genes cause the autosomal-recessive (AR) Alport syndrome, a similar phenotype to that of X-linked inheritance in males [45,46] or the “autosomal dominant” (AD) Alport syndrome, a less severe phenotype with persistent hematuria but without extrarenal manifestations. The gene discussed is COL4A4; the disease is Alport syndrome.