Abstract
X-linked adrenoleukodystrophy (ALD) is a peroxisomal disorder caused by mutations in the ABCD1 gene and characterized by impaired very long-chain fatty acid beta-oxidation. Clinically, male patients develop adrenal failure and a progressive myelopathy in adulthood, although age of onset and rate of progression are highly variable. Additionally, 40% of male patients develop a leukodystrophy (cerebral ALD) before the age of 18 years. Women with ALD also develop a myelopathy but generally at a later age than men and with slower progression. Adrenal failure and leukodystrophy are exceedingly rare in women. Allogeneic hematopoietic cell transplantation (HCT), or more recently autologous HCT with ex vivo lentivirally transfected bone marrow, halts the leukodystrophy. Unfortunately, there is no curative treatment for the myelopathy. In the following chapter, the biochemistry, pathology, and clinical spectrum of ALD are discussed in detail.