In particular, the COL4A1-related disorders have been associated to different phenotypes (porencephaly; brain small-vessel disease with hemorrhage; angiopathy with nephropathy, aneurysms, and muscle cramps —HANAC-syndrome; tortuosity of retinal arteries; non-syndromic congenital cataract) with a known wide intrafamilial variability. The gene discussed is COL4A1; the disease is aneurysm.