What is Adrenoleukodystrophy?

Adrenoleukodystrophy (ADL) is a rare genetic disease which affects the brain and adrenal glands. There are several different forms of adrenoleukodystrophy, ranging from very severe neonatal and childhood forms which usually kill to more mild variations which can appear later in life. It is possible for numerous people in the same family to have slightly different forms of this condition.

Patients with adrenoleukodystrophy have functional problems with their peroxisomes, the structures in cells which are responsible for breaking down fats. Certain types of fat start to accumulate in the body because they cannot be broken down. In the adrenal glands, the fats interfere with the production of hormones, and in the brain, they contribute to the breakdown of the myelin sheaths which protect the nerves. Additionally, because the fats cannot be broken into useful components, the body cannot synthesize more myelin, because it needs the compounds found in the fats to do so.

This genetic condition is sex-linked, and appears primarily in boys and men. Female carriers generally do not develop the condition, or they experience mild symptoms later in life, because they only carry the gene on one X chromosome, and their second X chromosome without the gene suppresses the expression of the defective gene. Around one in 100,000 people develops adrenoleukodystrophy.

People with this condition develop adrenal insufficiency in the form known as Addison's disease, which leads to a variety of health problems. The neurological damage causes speech problems, stumbling gait, coordination issues, bad memory, visual problems, seizures, dementia, deafness, and behavioral abnormalities. The damage is progressive, and when the condition appears in childhood, the prognosis is usually very poor. Individuals who develop adrenoleukodystrophy later in life stand a better chance of survival, and they have much milder symptoms.

There is no cure for adrenoleukodystrophy. Supportive measures such as hormone therapy are used to address the health problems associated with the disease, and bone marrow transplants appear to have some promise. Some people have also had success with Lorenzo's oil, a compound named for a famous adrenoleukodystrophy patient which is designed to slow the progress of the damage, although studies have suggested that Lorenzo's oil may not be effective in the long term.

Genetic therapies may someday be utilized to treat ADL patients. Parents can also undergo genetic testing to determine whether or not they are carriers of the disease. For those who wish to avoid having children with this condition, parents who carry the gene can use assisted reproductive technology to get pregnant and choose pre-implantation genetic diagnosis, in which only embryos free of the gene are chosen for implantation.