Dysfunction of ABCD1 results in increased levels of saturated (C24∶0 and C26∶0) and monounsaturated (C26∶1) VLCFAs in the plasma and tissues of X-ALD patients, due to the reduced β-oxidation of VLCFAs in peroxisomes [7]. The gene discussed is ABCD1; the disease is X-linked adrenoleukodystrophy.