Genetic testing for a NOTCH3 variant to confirm the diagnosis of cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) syndrome in a patient may be considered medically necessary under the following conditions:
Clinical signs, symptoms, and imaging results are consistent with CADASIL, indicating that the pretest probability of CADASIL is at least in the moderate-to-high range (see the Policy Guidelines section); and
The diagnosis of CADASIL is inconclusive following alternative methods of testing, including magnetic resonance imaging.
For individuals who are asymptomatic with a family member with a diagnosis of CADASIL syndrome:
If there is a family member (first- and second-degree relative) with a known variant, targeted genetic testing of the known NOTCH3 familial variant may be considered medically necessary.
If the family member’s genetic status is unknown, genetic testing of NOTCH3 (see Policy Guidelines section) may be considered medically necessary.
Genetic testing for a NOTCH3 variant to confirm the diagnosis of CADASIL syndrome in all other situations is considered investigational.
