The diagnosis technique for leukodystrophy differs depending on the nature of the suspected illness. In all cases, a physician is likely to perform a complete physical examination and to compile a thorough medical history. A physician will pay special attention to the signs and symptoms that are characteristic of various forms of leukodystrophy and ask whether there is a family history of the disease. Leukodystrophy is an inherited disease, which means that the combination of family history with signs and symptoms is a potential indicator of the disease.

To confirm a diagnosis of leukodystrophy, a physician may perform several tests, including:

• Blood tests. These can help diagnose most forms of leukodystrophy. Some blood tests look for mutated genes. Other blood tests look for abnormal levels of chemicals in the blood or other indicators of leukodystrophy.
  
  
• Skin biopsies. These are frequently used to diagnose leukodystrophies. Like blood tests, a skin biopsy can be used to look for evidence of mutated genes. A skin biopsy can also reveal other indicators of leukodystrophy, such as the accumulation of granular material in the tissues that is characteristic of CADASIL (cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy).
  
  
• Imaging tests. Various imaging tests may be used to either diagnose a condition, or to look for complications associated with leukodystrophy, including abnormalities in the myelin sheath (the fatty covering that protects nerve cells). Such tests include computed axial tomography (CAT scans) and magnetic resonance imaging (MRI).

Other procedures that are used to diagnose leukodystrophy include a spinal tap (in which a sample of cerebrospinal fluid is obtained) and electroencephalography (EEG), a procedure that measures a patient’s brain waves.

Some types of leukodystrophy may be diagnosed before birth using prenatal testing such as amniocentesis. This is a procedure that is performed by inserting a hollow needle through the abdominal wall into the uterus. A small amount of fluid is then withdrawn from the sac surrounding the fetus and tested for indicators of leukodystrophy.