ABCD1 and X-linked adrenoleukodystrophy: X-linked adrenoleukodystrophy, X-ALD (OMIM: 300,100, ICD: E71.33) is a rare disease with estimated prevalence of 1 in 15,000 individuals caused by mutations in ABCD1 - an X chromosome gene (Xq28) which codes for the ALD protein.