Cerebral autosomal recessive arteriopathy with subcortical infarcts and white matter lesions (CARASIL) is a monogenic CSVD, determined by mutations in the high-temperature requirement A serine protease 1 gene (HTRA1) which is located on chromosome 10 (10q26) and encodes the high-temperature requirement serine protease. Here, PRSS1 is linked to CARASIL.