What is CADASIL?
CADASIL (Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy) is the most common monogenic cerebral small vessel disease, caused by mutations in the NOTCH3 gene on chromosome 19, leading to progressive vascular smooth muscle cell destruction, recurrent strokes, cognitive decline, and dementia. 1, 2
Genetic Basis and Epidemiology
- CADASIL is caused by single missense mutations or small deletions in the NOTCH3 gene, resulting in gain or loss of cysteine residues in the epidermal growth factor-like repeats of the Notch3 receptor 3
- Over 280 distinct pathogenic mutations have been identified to date 1
- The disease was historically considered rare (prevalence 1.3-4.1 per 100,000 adults), but recent large-scale genomic studies reveal much higher prevalence of pathogenic NOTCH3 variants in the general population, with highest risk among Asians 1
- CADASIL was the first monogenic cerebral small vessel disease gene discovered (NOTCH3 in 1996) 4
Pathophysiology
- The hallmark pathological feature is accumulation of granular osmiophilic material in arterial walls throughout the body, including dermal arteries 3
- Progressive destruction of vascular smooth muscle cells leads to wall thickening, fibrosis, and luminal narrowing in small and medium-sized penetrating arteries 3
- Reduced cerebral blood flow causes lacunar infarcts, predominantly in basal ganglia and fronto-temporal white matter 3
- The exact pathogenesis remains unclear, with proposed mechanisms including aberrant NOTCH3 signaling, toxic protein aggregation, and abnormal matrisomes 1
Clinical Manifestations
The typical clinical course progresses through distinct phases:
- Migraine with aura appears first in approximately one-third of patients 5, 3
- Recurrent strokes and transient ischemic attacks emerge between ages 30-50 years 3
- Mood disorders and progressive cognitive impairment develop, leading to subcortical vascular dementia and disability 5
- Less common presentations include seizures (rarely as initial manifestation), non-convulsive status epilepticus, and facial palsy 6, 7
Important caveat: Disease severity and age at onset vary significantly even among individuals carrying identical NOTCH3 mutations, and no clear genotype-phenotype correlation has been established 1
Diagnostic Features
Characteristic neuroimaging findings on brain MRI include:
- Subcortical lacunar lesions and white matter hyperintensities in the anterior temporal lobe or external capsule—these features are particularly useful for differentiating CADASIL from sporadic stroke 1
- The number of lacunes and degree of brain atrophy predict clinical outcomes 1
Definitive diagnosis requires:
- Genetic testing demonstrating pathogenic NOTCH3 mutations 8
- Skin biopsy showing granular osmiophilic material in dermal arteries (pathognomonic finding) 3
Systemic Involvement
- While NOTCH3 mutations primarily cause cerebral small vessel disease, the arteriopathy is generalized and affects vessels throughout the body 3
- Unlike other monogenic cerebral small vessel diseases (COL4A1, TREX1, HTRA1, ADA2, CTSA), NOTCH3/CADASIL has minimal symptomatic extracerebral phenotypes, though asymptomatic skin involvement occurs 4
Management Approach
Current management focuses on vascular risk factor control and symptomatic treatment, as no disease-modifying therapies exist:
- Hypertension management is the only intervention shown to reduce cerebral small vessel disease risk 4
- Antiplatelet therapy (aspirin) and statin therapy for secondary stroke prevention 6
- Multidisciplinary care involving neurology, genetic counseling, physical therapy, and psychiatry for depression/anxiety management 6
- Genetic counseling for affected individuals and at-risk family members 8, 6
Critical pitfall: Unlike some other monogenic cerebral small vessel diseases (ADA2, COL4A1, TREX1), no specific disease-modifying treatments currently exist for CADASIL 4