From: Genetics Home Reference
The ABCD1 gene is located on the X chromosome, and it encodes the adrenoleukodystrophy protein (ALDP). ALDP is located in the membranes of cell structures called peroxisomes. Peroxisomes are small sacs within cells that process many types of molecules. ALDP brings a group of fats called very long-chain fatty acids (VLCFAs) into peroxisomes, where they are broken down.
More than 650 mutations in the ABCD1 gene have been found to cause X-linked adrenoleukodystrophy (many of which lack dbSNP rs-ids though). This condition is characterized by varying degrees of cognitive and movement problems as well as hormone imbalances. The mutations that cause X-linked adrenoleukodystrophy prevent the production of any ALDP in about 75 percent of people with this disorder. Other people with X-linked adrenoleukodystrophy can produce ALDP, but the protein is not able to perform its normal function. With little or no functional ALDP, VLCFAs are not broken down, and they build up in the body. The accumulation of these fats may be toxic to the adrenal glands (small glands on top of each kidney) and to the fatty layer of insulation (myelin) that surrounds many nerves in the body. Research suggests that the accumulation of VLCFAs triggers an inflammatory response in the brain, which could lead to the breakdown of myelin. The destruction of these tissues leads to the signs and symptoms of X-linked adrenoleukodystrophy. Note that there are three distinct types of X-linked adrenoleukodystrophy: a childhood cerebral form, an adrenomyeloneuropathy type, and a form called Addison disease only.
The prevalence of X-linked adrenoleukodystrophy is 1 in 20,000 to 50,000 individuals worldwide. This condition occurs with a similar frequency in all populations.
In popular culture, X-linked adrenoleukodystrophy has made an appearance through the 1993 movie 'Lorenzo's Oil', based on the true story of two parents and their search for a cure for their son. In the movie, the two parents were played by Nick Nolte and Susan Sarandon.
In 1989, the Odone's established The Myelin Project, a charity advancing research, advocacy, and family support for adrenoleukodystrophy (ALD) and adrenomyeloneuropathy (AMN). Efforts continue to find a cure.
A 10 minute YouTube video describing ALD can be found here.