Metachromatic Leukodystrophy and Globoid Cell Leukodystrophy

Metachromatic leukodystrophy (MLD) and globoid cell leukodystrophy (GLD) are autosomal recessively inherited disorders caused by the deficiency of arylsulfatase A or galactocere brosidase, respectively. The incidence of MLD is estimated to be about 0.6–1.45 in 100000 live newborns, depending on the country investigated. The incidence of GLD in the United States and northern Europe is estimated to be between 0.4 and 1.35 in 100000 live births. In MLD, a certain phenotype–genotype correlation exists, but it is limited. In humans, symptoms may also be caused by neuronal storage before symptoms due to demyelination dominate the clinical picture. The clinical phenotype of MLD and GLD is mainly due to the global and progressive loss of myelin. Central and cerebellar white matter signal changes are characteristic for the infantile forms of GLD. In general, for both disorders, the initial diagnosis depends on the demonstration of the respective enzyme deficiencies in leukocytes.