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- X-linked adrenoleukodystrophy (X-ALD) is a rare neurodegenerative disorder due to mutations of the ABCD1 gene that result in loss of function of the encoded ALD protein (ALDP). The incidence of X-ALD is 1/17,000 births. Because the gene defect is located on the X chromosome, males are usually more affected than women (who have two copies of the X chromosome). ALDP deficiency impairs the metabolism of very long-chain fatty acids (VLCFA) resulting in the accumulation of VLCFA in plasma and tissues.
- The two main clinical phenotypes of X-ALD are adrenomyeloneuropathy (AMN) and inflammatory cerebral ALD that presents either in boys or in adult males. Both phenotypes occur frequently within the same family.
- AMN is the most frequent phenotype of X-ALD (60% of cases in males). Virtually all males with X-ALD who reach adulthood develop AMN, usually in the 3rd and 4th decade. Initially, the neurologic disability is slowly progressive. As a consequence of spinal cord involvement, AMN males develop progressive stiffness and weakness of the legs, gait imbalance, pain in the lower limbs and sphincter disturbances (mostly urinary).
- Treatment of AMN is often limited to treatment of symptoms (medications against spasticity, sphincter dysfunctions, impotence and neuropathic pain) and active physical rehabilitation.“Lorenzo’s oil” (LO) is a 4:1 mixture of glyceryl trioleate and glyceryl trierucate, which when given orally and combined with a diet reduction of VLCFA, has been shown to normalize the level of VLCFA in plasma. However, no proof exists that this treatment is able to improve, halt or even slow down the progression of the disease.