De novo mutation in the notch3 gene causing CADASIL

CADASIL, an autosomal dominant arteriopathy responsible for stroke and dementia, is caused by strongly stereotyped mutations in the Notch3 gene. We report a patient with a condition strongly suggestive of CADASIL (migraine, stroke, and white matter abnormalities), except that this patient did not have any first-degree relatives with similar symptoms. This patient carried a heterozygous Arg182Cys mutation in the Notch3 gene; this mutation was absent in his two biological parents. These data demonstrate the occurrence of a de novo noninherited mutation in the Notch3 gene, which indicates that CADASIL should not be rejected in the absence of a family history. Therefore, our finding suggests that CADASIL may be more frequent than anticipated.