<unk>  <unk>  is a disease linked to the X chromosome. It is a result of fatty acid buildup caused by a defect in the very long chain of fatty acids transporter in peroxisomes, which then causes damage to the myelin sheath of the nerves, resulting in seizures and hyperactivity. Other symptoms include problems with speaking, listening, and understanding verbal instructions. In more detail, it is a disorder of peroxisomal fatty acid beta oxidation which results in the accumulation of very long chain fatty acids in tissues throughout the body. The most severely affected tissues are the myelin in the central nervous system, the adrenal cortex, and the Leydig cells in the testes. Clinically,<unk>  is a heterogeneous disorder, presenting with several distinct phenotypes, and no clear pattern of genotype–phenotype correlation. As an X-linked disorder,<unk>  presents most commonly in males, however approximately 50% of heterozygote females show some symptoms later in life. Approximately two-thirds of<unk>  patients will present with the childhood cerebral form of the disease, which is the most severe form. It is characterized by normal development in early childhood, followed by rapid degeneration to a vegetative state. The other forms of<unk>  vary in terms of onset and clinical severity, ranging from adrenal insufficiency to progressive paraparesis in early adulthood (this form of the disease is typically known as adrenomyeloneuropathy).<unk>  is caused by mutations in ABCD1, a gene located on the X chromosome that codes for<unk> , a peroxisomal membrane transporter protein. The exact mechanism of the pathogenesis of the various forms of<unk>  is not known. Biochemically, individuals with<unk>  show very high levels of unbranched, saturated, very long chain fatty acids, particularly cerotic acid (26:0). The level of cerotic acid in plasma does not correlate with clinical presentation. Treatment options for<unk>  are limited. Dietary treatment is with Lorenzo's oil. For the childhood cerebral form, stem cell transplant and gene therapy are options if the disease is detected early in the clinical course. Adrenal insufficiency in<unk>  patients can be successfully treated.<unk>  is the most common peroxisomal inborn error of metabolism, with an incidence estimated between 1:18,000 and 1:50,000. It does not have a significantly higher incidence in any specific ethnic groups.
Adrenoleukodystrophy
Hereditary inclusion body myopathy
Inclusion body myositis
Mitochondrial myopathy
Familial amyloid neuropathy
Familial amyloid polyneuropathy
Charcot–Marie–Tooth disease
Lambert–Eaton myasthenic syndrome