COL4A1 and porencephaly: Collagen type IV alpha 1 chain (COL4A1) related disorders were characterized as cerebral SVD with diverse disease phenotypes that include porencephaly, seizures, dementia, intellectual disability, migraine, stroke, visual impairment (visual loss, cataract, glaucoma), muscle dysfunction or hereditary angiopathy with nephropathy, aneurysms, and muscle cramps (HANAC) syndrome [32,116].