Brain Small Vessel Disease 1, also known as col4a1-related retinal arteriolar tortuosity-infantile hemiparesis-autosomal dominant leukoencephalopathy syndrome, is related to brain small vessel disease 3 and brain small vessel disease 2. An important gene associated with Brain Small Vessel Disease 1 is COL4A1 (Collagen Type IV Alpha 1 Chain), and among its related pathways/superpathways are Extracellular matrix organization and Cytoskeleton remodeling Regulation of actin cytoskeleton by Rho GTPases. Affiliated tissues include brain and fetal brain, and related phenotypes are muscle and respiratory system