When do you consider testing with stroke gene panels in young stroke patients?

Broadly, I ask for genetic testing only when I have a specific diagnosis in mind. This testing is not routine in my practice. Examples are:

1. A patient is referred for white matter lesions found on brain MR and a transient neurological episode. The question of CADASIL(NOTCH-3) or related disorders is raised like CARASIL(HTRA-1). I will ask for our vascular white matter disease panel which includes testing for these conditions. I use the MR and the age of the patient to guide these requests. In a patient in middle age (over 50) and who has anterior temporal lobe and/or external capsule lesions, then I have a much stronger suspicion for CADASIL. Younger patients with CADASIL may not show lesions in those regions.
2. A patient with spontaneous (at...

I send for genetic testing on the following young adults:

Those without any other risk factors and recurrent small vessel strokes, white matter changes, microbleeds, and/or history personal or family of any one of the following: early cognitive decline, migraines, and mood disorders for CADASIL (NOTCH3). Even if they have minimal white matter changes but have an episode of confusional migraine and encephalopathy. That prompts me to consider this diagnosis and take a thorough family and personal history. Similar MRI features but with also premature alopecia, spondylitis deformans, seizure, and cognitive difficulties, CARASIL (HTRA-1). Those with mixed patterns and/or with predominantly brainstem and cerebellar peduncle microvascular changes,...