COL4A1 and hereditary optic atrophy: Mutations in COL4A1 have been associated with small-vessel brain disease including porencephaly, schizencephaly, cerebrovascular disease, ophthalmological disorders (retinal arterial tortuosity, congenital cataract, anterior segment dysgenesis, glaucoma, microphthalmia/anophthalmia, optic atrophy, and ONH), but also with renal and muscular abnormalities [32,36,37].