HTRA1 and CARASIL: CARASIL (cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy), which causes lacunar stroke, leukoaraiosis, and early onset vascular dementia, has been shown to results from mutations in the HtrA serine protease 1 (HTRA1) gene, which is involved in TGF-β signalling [35].