Hereditary causes of ischemic cerebral small vessel disease.

Hereditary types of ischemic cerebral subcortical small vessel disease (SSVD) are rare, usually autosomal dominant, diseases, due to an abnormality in vessel wall synthesis. They may present with various combinations of migraine with aura, ischemic events (transient ischemic attacks, lacunar strokes) and progressively worsening ischemic lesion load in brain imaging. Eventually, vascular cognitive impairment (usually of the frontal-subcortical type) develops, frequently accompanied by behavioral-psychiatric symptoms and bilateral pyramidal and pseudobulbar signs leading to severe disability and premature death. In some patients, microbleeds and hemorrhagic strokes may be present. Despite their rarity, these disorders offer a statistically homogeneous population (usually without additional pathology such as Alzheimer's disease), suitable for the study of vascular cognitive impairment. The few studies on the relative frequency of these disorders indicate that the most frequent (or rather the least rare), accounting for more than half of patients, is CADASIL, due to mutations of the NOTCH3 gene, followed by COL4A1/A2-related disease, autosomal dominant forms of HTRA1-related disease and leucoencephalopathies with calcifications and cysts. Mutations of TREX1, GLA, FOXC1 and CARASIL are less frequent. Despite the genetic nature of these disorders, their phenotype, severity and rate of progression may be adversely affected by classical cardiovascular risk factors such as hypertension, diabetes, dyslipidemia and smoking and control of these risk factors is strongly advised for all patients.