ABCD1 and X-linked adrenoleukodystrophy: Once the ABCD1 gene was known, the sequencing of the ABCD1 gene was used diagnostically as analysis of the family ABCD1 mutation improves the diagnosis of ALD women as the plasma VLCFA test has a 20% false negative rate (Boehm, Cutting, Lachtermacher, Moser, & Chong, 1999).