COL4A3 variants in children were associated with severe IgAN, recurrent flares, gross hematuria, and faster decline in kidney function.92 These variants may explain recurrent gross hematuria in children with concurrent infections (synpharyngitic hematuria), similar to Alport syndrome.92 Since gross hematuria is the key clinical feature distinguishing childhood IgAN from adult IgAN, variants in type IV collagen may be the distinct disease mechanism explaining this difference. The gene discussed is COL4A3; the disease is Hematuria.