Adrenoleukodystrophy describes any of several closely related inheritable disorders of the breakdown ( metabolism ) of certain fats (long chain fatty acid) that affects the adrenal glands , nervous system, and testes .
Alternative Names
X-linked adrenoleukodystrophy; Melanodermic leukodystrophy; Neonatal adrenoleukodyrstophy; NALD
Causes, incidence, and risk factors
Adrenoleukodystrophy is transmitted as an X-linked trait (the neonatal form is by autosomal recessive transmission). Its incidence is estimated at 1 out of 20,000 to 1 in 50,000 and affects all races. The metabolic defect is the accumulation of long chain fatty acids in the nervous system, adrenal gland, and testes , where the accumulated material disrupts normal activity. There are several (seven recognized) different forms of the disease. The neonatal form appears shortly after birth and includes seizures and delayed neurological development with death occurring in infancy or young childhood. The childhood cerebral form (around 4-8 years) appears in mid-childhood, and the other forms appear during adolescence . About 33% of affected people develop neurological symptoms and about 50% develop abnormal adrenal function. In the childhood form, early symptoms include hyperactivity , difficulty at school, difficulty understanding spoken material, deterioration of handwriting, crossed eyes ( strabismus ), and possibly seizures . As the disease progresses, further signs of damage to the white matter of the brain appear and include changes in muscle tone, stiffness and contracture deformities , swallowing difficulties , and coma . The other major component of the childhood form and all other forms of adrenoleukodystrophy is the development of impaired adrenal gland function (similar to Addison disease). There is a deficiency of steroid hormones. This is a very significant development but one that can be adequately treated with corticosteroids.
Signs and tests
blood levels showing elevated long chain fatty acids skin biopsy and fibroblast culture showing elevated levels of long chain fatty acids MRI of the head showing damage to the white matter of the brain (white matter is a specific type of brain tissue)
head CT shows damage to the white matter of the brain chromosome study (neolatal form - defects at chromosome 7q21-q22)
Treatment
Adrenal dysfunction is treated with supplemental steroids (such as cortisol). A specific treatment for adrenoleukodystrophy is not available, but a diet low in long chain fatty acids and the administration of special oils has been demonstrated to lower the blood levels of the long chain fatty acids. These oils are referred to as Lorenzo's oil, after the son of the family who discovered the treatment. This regimen is presently under evaluation for the treatment of adrenoleukodystrophy.
Expectations (prognosis)
The childhood form of adrenoleukodystrophy is a progressive disease that leads to a vegetative state in approximately two years after neurologic symptoms develop. The child may live in this condition for as much as ten years until death occurs. The later onset forms are significantly less dangerous.
Calling your health care provider
Call your health care provider if your child develops symptoms suggestive of adrenoleukodystrophy or if you have a child with adrenoleukodystrophy who is experiencing increased difficulty.
Prevention
Genetic counseling is recommended for prospective parents with a family history of adrenoleukodystrophy. The carrier state in females can be diagnosed in 85% of the cases using a very long fatty acid assay and a DNA probe study by specialized laboratories. Intrauterine diagnosis of adrenoleukodystrophy is available and done by evaluation of cells from chorionic villus sampling or from amniotic cells ( amniocentesis ).