To provide an overview of the phenotype of 2 clinically, radiologically, and pathologically similar leukodystrophies, adult-onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP) and alanyl-transfer RNA synthetase 2 mutation–related leukodystrophy (AARS2-L), and highlight key differentiating features. This evidence concerns the gene AARS2 and leukodystrophy.