In a case report study, a homozygous variant of c.847G>T in the HtrA serine protease 1 (HTRA1) gene was found in a patient with symptoms of Cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy (CARASIL) and WMHs in MRI [56]. The gene discussed is PRSS1; the disease is CARASIL.