Adrenoleukodystrophy is a progressive condition that affects the adrenal glands, the glands atop the kidneys responsible for the production of adrenalin, and myelin, which insulates the nerves in the brain and spinal cord.
Adrenoleukodystrophy (ALD) was first described in the early 1900s and was originally called Schilder-Addision disease. It is named for the different parts of the body that are affected; "adreno" refers to the adrenal glands, "leuko" is the Greek word for white (myelin is often called the white matter in the brain and spinal cord), and "dystrophy" meaning impaired growth. Therefore, this disease affects the adrenal glands and the growth of the myelin in the brain and spinal cord. There is a wide range in the severity of symptoms. ALD mainly affects males, but occasionally females have mild or moderate symptoms.
Causes and effects
ALD is caused by problems in the peroxisomes. The peroxisomes are tiny structures in cells that help break down large molecules of fats into smaller ones so that they can be used by the body. In ALD the peroxisomes cannot break down a type of fat called very long chain fatty acids (VLCFA). There are two types of problems that occur because the VLCFA are not broken down. First, because the VLCFA cannot be broken down, they accumulate throughout the body, especially in the brain and the adrenal glands. Very high levels of VLCFA are also seen in the blood. The second type of problem occurs because the fats that are usually made when VLCFA are broken down are not produced. This is in part what happens in the adrenal glands and in the myelin.
The adrenal glands are located on top of each kidney in the abdomen. Part of the job of the adrenal glands is to use cholesterol (a type of fat made in the body when VLCFA are broken down) to make a few different steroids—chemical combinations that form the basis of hormones, body acids, and anabolic agents. The steroids are used to help the body properly use sodium and potassium and to break down proteins, carbohydrates, and other fats. Some of these steroids are also involved with sexual development and function.
The insulation that surrounds the nerves is called myelin and is also affected by the VLCFA not being broken down. Myelin is made up of a number of different proteins and fats. Normally the VLCFA break down and produce fats that make up part of the myelin. When the VLCFA cannot break down, the fats necessary to make the myelin are not made and the myelin is abnormal. In addition, for reasons not well understood, there is also active breakdown of myelin, also known as demyelination.
Karen M. Krajewski MS, CGC, The Gale Group Inc., Gale, Detroit,