AARS2 and CADASIL: The most frequently mutated genes were EIF2B4/5 causing vanishing white matter (VWM), CSF1R, causing adult onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP), AARS2, causing a leukoencephalopathy with ovarian failure and NOTCH3, causing cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) (Fig. 1).