Overview

Metachromatic leukodystrophy is a rare hereditary (genetic) disorder that causes fatty substances (lipids) to build up in your brain, spinal cord and peripheral nerves.

This buildup is caused by a deficiency of an enzyme that helps break down lipids. Your brain and nervous system progressively lose function.

Rarely, a deficiency in another kind of protein (activator protein) causes metachromatic leukodystrophy.

There are four types of metachromatic leukodystrophy. Each type occurs at different ages, but they may overlap. Each has different signs and symptoms.

The types and approximate age ranges include:

• Infantile form, occurring between birth and 12 months of age
• Late infantile form, occurring between a few months and 2 years of age
• Juvenile form, occurring between ages 3 and 16
• Adult form, occurring after age 16

Diagnosis

Your doctor will perform a physical examination and review your symptoms and medical history and check for signs of metachromatic leukodystrophy.

Your doctor may order tests to diagnose your condition. These tests also help determine how severe your condition is.

• Blood and urine tests. Blood tests look for an enzyme deficiency that causes metachromatic leukodystrophy.

  You may also have urine tests to check for buildup of fatty substances (lipids).

• Genetic tests. Your doctor will conduct genetic tests for mutations in the gene associated with metachromatic leukodystrophy.

  He or she may also recommend testing family members, particularly women who are pregnant (prenatal testing) for mutations in the gene.

• Nerve conduction study. This test measures electrical nerve impulses and function in your muscles and nerves by passing a small current through electrodes on your skin.

  Your doctor may use this test to look for nerve damage (peripheral neuropathy), which is common in people with metachromatic leukodystrophy.

• Magnetic resonance imaging (MRI). This test uses powerful magnets and radio waves to produce detailed pictures of your brain.

  Your doctor may use this test to determine if you have signs of metachromatic leukodystrophy, which has a characteristic striped pattern (tigroid) of abnormal white matter (leukodystrophy) in your brain.

• Psychological and cognitive tests. Your doctor may test your psychological and thinking (cognitive) abilities. These tests may help determine how the condition affects your brain function.

Source: http://www.mayoclinic.com