ABCD1 and X-linked adrenoleukodystrophy: X-linked adrenoleukodystrophy (X-ALD; MIM# 300100) is a progressive neurodegenerative disease that is caused by mutations in the ABCD1 gene, encoding ALD protein (ALDP), an (ATP)-binding-cassette (ABC) transporter located in the peroxisomal membrane [1].