CADASIL (cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy) is the most common form of hereditary stroke disorder, and is thought to be caused by mutations of the Notch 3 gene on chromosome 19.[1]. The disease belongs to a family of disorders called the Leukodystrophies.
Since CADASIL is a systemic arteriopathy, evidence of blood vessel damage is seen in small- and medium-sized arteries. Therefore, skin biopsies have been used for diagnosis;
So I think It's better to code like 437.9, 434.91 & 323.82 or 323.9.
Hey, also please check the tabular list for this codes, and match the coditions/causes for CADASIL that are mentioned in your chart , viz., due to viral/infectious diseases or due to drug or vaccine. I'm sure, you get the correct code.
Hope this helps.