HTRA1 and Leukoencephalopathy: Among the prominent phenotypes linked to mutations within the HTRA1 gene are the “classical” CARASIL syndrome, which is inherited through an autosomal recessive mechanism, and cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy, type 2, also referred to as HTRA1-CSVD.[7] The classical CARASIL syndrome is primarily caused by homozygous or compound heterozygous mutations that adhere to an autosomal recessive inheritance pattern.