Recent advances suggest the existence of several autosomal dominantly inherited forms of cerebrovascular disorders. Mutations in diverse genes may induce direct pathological changes in intracranial vessels to cause cerebral ischaemic or haemorrhagic strokes leading to cognitive impairment and dementia. Similar pathology may also be caused by systemic vascular disease resulting from mutations and polymorphisms in genes that regulate cardiovascular physiology, blood coagulation and metabolic functions. The most common form of familial stroke appears to be CADASIL or cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy. CADASIL is an arterial disease that has been linked to nucleotide substitutions and deletions in the Notch 3 gene. The pathogenesis of the disorder or how the mutations lead to cerebral infarcts and dementia is not known. However, elucidation of the microvascular pathology associated with such genetic disorders not associated with physiological risk factors for cardiovascular disease or stroke can bear much light on primary vascular mechanisms that lead to ischaemic blood flow and neuronal vulnerability.