Accumulated unbranched, saturated (SFAs) and very long-chain fatty acids in the cell, as a consequence of mutated Abcd1, result in myelopathies as described for the X-linked adrenoleukodystrophy (X-ALD) or its milder form, the adrenomyeloneuropathy (AMN)18–20. This evidence concerns the gene ABCD1 and X-linked adrenoleukodystrophy.