The neurobiology of X-linked adrenoleukodystrophy, a demyelinating peroxisomal disorder.

Adrenoleukodystrophy (ALD) is caused by mutations in an ATP-binding-cassette transporter located in the peroxisomal membrane, which result in a fatal demyelinating disease in boys and a milder phenotype in men and some heterozygous women. There is no molecular signature to indicate a particular clinical course. The underlying molecular mechanisms of this disease have yet to be targeted clinically. Is the increase in very-long-chain fatty acids (VLCFA) the disease trigger? Why is there no phenotype in ALD null mice that show this increase? Do VLCFA destabilize human myelin, once formed, and lead to the inflammation seen in this genetic disease? Bone-marrow transplantation might save a child by providing normal brain macrophages and allowing myelin regeneration early in disease. The processes that underlie ALD challenge neuroscientists to elucidate peroxisomal transporter functions in the nervous system and to pursue the gene-transfer strategies leading to remyelination until a preventive therapy emerges.