Biallelic, autosomal recessively inherited mutations in GLIALCAM were described in a proportion of the patients with the classic phenotype of Megalencephalic leukoencephalopathy with subcortical cysts (MLC2A, MIM 613925) associated with ataxia, spasticity, and intellectual disability [22] and no identifiable variants in the more commonly involved MLC1 gene (MIM 605908). Here, HEPACAM is linked to leukoencephalopathy, megalencephalic.