Pathogenic mutations, such as Neurogenic locus notch homolog protein 3(NOTCH3) gene and HtrA Serine Peptidase 1(HTRA1) gene, have been reported in certain types of monogenetic stroke syndromes, such as cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy(CADASIL) and cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy(CARASIL). The gene discussed is HTRA1; the disease is CARASIL.