COL4A4 and Alport syndrome: The remainder of those with Alport syndrome, about 5%, has autosomal dominant Alport syndrome (ADAS) due to heterozygous mutations in COL4A3 or COL4A4. However, the majority of those with heterozygous mutations of COL4A3 or COL4A4 have a form of familial hematuria that is usually nonprogressive: TBMN.