We thus concluded that the novel homozygote CLCN2 c.607 > T p.(Gly203Cys) variant causes CLCN2-related leukoencephalopathy in family members II:1, II:2 and II:4, but that all three also carried homozygous likely pathogenic CYP2U1 variants and that II:2 and II:4 had the full clinical phenotype of SPG56. The gene discussed is CLCN2; the disease is Leukoencephalopathy.