ARAS is a rare monogenic hereditary disease caused by homozygous or compound heterozygous mutations in the COL4A3 and COL4A4 genes.[9] The prevalence of ARAS is underestimated because many cases of childhood hematuria were diagnosed as being of thin basement membrane or benign familial hematuria. The gene discussed is COL4A4; the disease is hematuria, benign familial.