NOTCH3 and CADASIL: Total frequencies of variants of the general population were 0.4–11.7/1000, being approximately 100-fold higher than the prevalence of CADASIL, at 2–5/100,000, suggesting that NOTCH3 variant carriers in general populations may be asymptomatic or preclinical CADASIL patients, or the variant may be of low penetrance [8].