ABCD1 and peroxisomal disease: X-linked adrenoleukodystrophy (X-ALD; OMIM:300100), a rare and complex peroxisomal disorder, is distinguished by progressive demyelination of the cerebral white matter, a gradual myeloneuropathy evolution, and irregularities in adrenal cortex function.[1,2] It arises due to a deficiency in the ATP-binding cassette sub-family D member 1-a protein encoded by the ABCD1 gene, leading to impairment in the β-oxidation of very long-chain fatty acids (VLCFA).