Cerebral Amyloid Angiopathy (CAA): Hereditary vs. Sporadic Causes and Risk Factors

Understanding Cerebral Amyloid Angiopathy

Cerebral amyloid angiopathy (CAA) is a condition characterized by the buildup of amyloid protein in the walls of brain arteries. It can occur in two primary forms: sporadic and hereditary.

Sporadic CAA

Sporadic CAA is the most common form, typically affecting older adults without a family history of the disease. It is believed to result from a complex interplay of genetic susceptibility and environmental factors, such as age-related changes in protein clearance.

Hereditary CAA

Hereditary CAA is a rare, genetically driven form caused by specific gene mutations passed down through families. It tends to be more severe, with an earlier onset of symptoms—often in mid-adulthood—compared to the sporadic type.

Key Genetic Mutations

• NOTCH3: The most frequent cause, accounting for approximately 50% of hereditary CAA cases (associated with CADASIL syndrome).
• COL4A1 & COL4A2: Mutations in these collagen genes can lead to familial CAA and related small vessel diseases.
• TREM2: Variants in this gene have been linked to increased risk for CAA and other neurodegenerative conditions.

Genetic counseling is recommended for individuals with a family history of early-onset stroke or CAA to assess risk and guide management.