ABCD1 and X-linked adrenoleukodystrophy: Adrenoleukodystrophy (ALD) has a variable and unpredictable clinical course.1 It is caused by pathogenic variants in ABCD1 causing deficient β-oxidation of saturated very-long-chain fatty acids (VLCFAs).2, -, 4 VLCFAs in plasma are a diagnostic marker.5,6 Patients are asymptomatic at birth but develop symptoms as the disease progresses.