Leukodystrophy is group of disorders characterized by degeneration of the white matter in the brain. The leukodystrophies are caused by imperfect growth or development of the myelin sheath, the fatty covering that acts as an insulator around nerve fibers. Myelin in the CNS is produced by oligodendrocytes. When damage occurs to white matter tissue immune responses can lead to inflammation in the CNS, along with loss of myelin.
The word leukodystrophy comes from the Greek roots
Types
Specific leukodystrophies include (ICD-10 codes are provided where available):
- (E71.3) adrenoleukodystrophy
- (E71.3) adrenomyeloneuropathy
- (E75.2) metachromatic leukodystrophy
- Hereditary CNS demyelinating disease
- (E75.2) Krabbe disease
- (E75.2) Pelizaeus-Merzbacher disease
- Canavan disease
- Leukoencephalopathy with vanishing white matter, also known as childhood ataxia with central nervous system hypomyelination (CACH) or vanishing white matter disease.
- Alexander disease
- (G60.1) Refsum disease
- cerebrotendineous xanthomatosis
xenobefantosis (G70.3)
Causes
Leukodystrophies are mostly inherited disorders. They may be inherited in a recessive, dominant, or X-linked manner, depending on the type of leukodystrophy. The individual articles on each leukodystrophy will describe the particular pattern of inheritance for that disease. There is also a fact sheet describing the different genetic inheritance patterns available from the United Leukodystrophy Foundation.
There are some leukodystrophies that do not appear to be inherited, but rather arise spontaneously. They are still caused by a mutation in a particular gene, but it means that the mutation was not inherited.
Known aggravators of leukodystrophy symptoms include radiation and certain chemotherapeutic treatments for cancer.
Pathophysiology
Clinical features
The most common symptom of a leukodystrophy disease is a gradual decline in an infant or child who previously appeared well. Progressive loss may appear in body tone, movements, gait, speech, ability to eat, vision, hearing and behaviour. There is often a slowdown in mental and physical development (though full, lasting cognizance has been observed, most notably in the case of Hunter Kelly, see 'Public Awareness'). Symptoms vary between specific types of leukodystrophy, as well as between individual patients, and may be difficult to recognise in the early stages of the disease.
Treatment
Epidemiology
Current research
One source of active (as of 2006) research is The Myelin Project. In addition, many research groups are studying the cellular processes of myelination, which may provide insights into leukodystrophy. Researchers in New York have successfully cured leukodystrophy in mice, using skin cells to repair damaged myelin sheaths. Researchers hypothesize that this treatment may possibly be used in curing human multiple sclerosis.
Public awareness
Jill Kelly and her husband, NFL quarterback Jim Kelly, founded Hunter's Hope after their son Hunter (1997-2005) was diagnosed with infantile Krabbe leukodystrophy.
Matthew and Michael Clark of Hull, UK are current sufferers. Their story was the subject of the Channel 4 documentary The Curious Case of the Clark Brothers.