Adrenoleukodystrophy (ALD) is a peroxisomal disorder characterized by white matter degeneration caused by adenosine triphosphate-binding cassette subfamily D member 1 (<i>ABCD1</i>) gene mutations, which lead to an accumulation of very-long-chain fatty acids (VLCFA). This evidence concerns the gene ABCD1 and X-linked adrenoleukodystrophy.