Dominant-negative mutations in the genes encoding collagen, type IV, alpha 1 (COL4A1; OMIM: *120130) and alpha 2 (COL4A2; OMIM: *120090) are pleiotropic and contribute to a broad spectrum of disorders including myopathy, glaucoma and cerebrovascular disease2, 3, 4, 5. The gene discussed is COL4A1; the disease is myopathy.