CTSA and CARASIL: Other rare forms include the Cerebral Autosomal Recessive Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CARASIL), an arteriopathy caused by mutations in the HTRA1 gene [72] and the Cathepsin A–Related Arteriopathy with Strokes and Leukoencephalopathy (CARASAL), an autosomal dominant disease caused by heterozygous mutation in the CTSA gene encoding cathepsin A [73].