X-linked adrenoleukodystrophy (ALD), a disorder characterized by primary adrenal insufficiency, hypothyroidism and neurological symptoms, is caused by pathogenic variants of ABCD1, a very-long-chain fatty acid (VLCFA) transporter, leading to VLCFA accumulation in the form of CE (99–101). Here, ABCD1 is linked to X-linked adrenoleukodystrophy.