ABCD1 and metachromatic leukodystrophy: Patients had metachromatic leukodystrophy (MLD) (ARSA gene; 139 patients [25% of cohort]), X-linked adrenoleukodystrophy (ABCD1; 111 patients [20%]), Krabbe disease (GALC; 56 patients [10%]), or Hurler disease (IDUA; 56 patients [10%]).