COL4A5 and kidney failure: Thus, a hypomorphic disease-causing COL4A5 variant may result in kidney failure in late middle age in a man, and a hypomorphic heterozygous disease-causing COL4A3 or COL4A4 variant may not be associated with microscopic haematuria, and/or lead to symptomatic disease only if found in trans with a second, overt, disease-causing variant.