Leukodystrophy refers to a group of disorders characterized by dysfunction of the white matter

White matter

White matter is one of the two components of the central nervous system and consists mostly of myelinated axons. White matter tissue of the freshly cut brain appears pinkish white to the naked eye because myelin is composed largely of lipid tissue veined with capillaries. Its white color is due to...

 of the brain. The leukodystrophies are caused by imperfect growth or development of the myelin

Myelin

Myelin is a dielectric material that forms a layer, the myelin sheath, usually around only the axon of a neuron. It is essential for the proper functioning of the nervous system. Myelin is an outgrowth of a type of glial cell. The production of the myelin sheath is called myelination...

 sheath, the fatty covering that acts as an insulator around nerve fibers. Myelin, from which the white matter of the brain takes its colour, is a complex substance made up of at least ten different chemicals. Each of the leukodystrophies is the result of a defect in the gene

Gene

A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...

 that controls the production or metabolism of one (and only one) of the component molecules of myelin.

The word leukodystrophy comes from the Greek roots leuko, white, dys, lack of, and troph, growth. Thus leukodystrophy describes a set of diseases that affect the growth or maintenance of the white matter.

Types

Specific leukodystrophies include (ICD-10

ICD

The International Statistical Classification of Diseases and Related Health Problems is a medical classification that provides codes to classify diseases and a wide variety of signs, symptoms, abnormal findings, complaints, social circumstances, and external causes of injury or disease...

 codes are provided where available):

• (E71.3) adrenoleukodystrophy
  Adrenoleukodystrophy
  Adrenoleukodystrophy is a rare, inherited disorder that leads to progressive brain damage, failure of the adrenal glands and eventually death. ALD is a disease in a group of genetic disorders called leukodystrophies, whose chief feature is damage to myelin...
  
  
• (E71.3) adrenomyeloneuropathy
  Adrenomyeloneuropathy
  Adrenomyeloneuropathy is a rare inherited disorder. It is a milder form of X-linked adrenoleukodystrophy . In adrenoleukodystrophy, young children generally exhibit cerebral dysfunction, with rapid progression to dementia and quadriparesis. Adrenomyeloneuropathy progresses more slowly, with...
  
  
• (E75.2) metachromatic leukodystrophy
  Metachromatic leukodystrophy
  Metachromatic leukodystrophy is a lysosomal storage disease which is commonly listed in the family of leukodystrophies. Leukodystrophies affect the growth and/or development of myelin, the fatty covering which acts as an insulator around nerve fibers throughout the central and peripheral nervous...
  
  
• Hereditary CNS demyelinating disease
  Hereditary CNS demyelinating disease
  A Hereditary CNS demyelinating disease is a demyelinating central nervous system disease that is primarily due to an inherited genetic condition...
  
  
  • (E75.2) Krabbe disease
    Krabbe disease
    Krabbe disease is a rare, often fatal degenerative disorder that affects the myelin sheath of the nervous system. This condition is inherited in an autosomal recessive pattern...
    
    
  • (E75.2) Pelizaeus-Merzbacher disease
    Pelizaeus-Merzbacher disease
    Pelizaeus–Merzbacher disease is a rare central nervous system disorder in which coordination, motor abilities, and intellectual function are delayed to variable extents.-Classification:...
    
    
  • Canavan disease
    Canavan disease
    Canavan disease, also called Canavan-Van Bogaert-Bertrand disease, aspartoacylase deficiency or aminoacylase 2 deficiency, is an autosomal recessive degenerative disorder that causes progressive damage to nerve cells in the brain. Canavan disease is also one of the most common degenerative...
    
    
  • Leukoencephalopathy with vanishing white matter
    Leukoencephalopathy with vanishing white matter
    Leukoencephalopathy with vanishing white matter is an autosomal recessive neurological disease. The cause of the disease are mutations in any of the 5 genes encoding subunits of the translation initiation factor EIF-2B: EIF2B1, EIF2B2, EIF2B3, EIF2B4, or EIF2B5...
    
    , also known as childhood ataxia with central nervous system hypomyelination (CACH) or vanishing white matter disease.
  • Alexander disease
    Alexander disease
    Alexander disease is a slowly progressing and fatal neurodegenerative disease. It is a very rare disorder which results from a genetic mutation and mostly affects infants and children, causing developmental delay and changes in physical characteristics....
    
    
• (G60.1) Refsum disease
• cerebrotendineous xanthomatosis
  Cerebrotendineous xanthomatosis
  Cerebrotendineous xanthomatosis or cerebrotendinous xanthomatosis , also called cerebral cholesterosis, is an autosomal recessive form of xanthomatosis.-Characteristics:...
  
  

Cause

Leukodystrophies are mostly inherited disorders, meaning that it is passed on from parent to child. 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 separate 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 just means that the mutation was not inherited. In this case, the birth of one child with the disease does not necessarily increase the likelihood of a second child having the disease.

Symptoms

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 behavior. There is often a slowdown in mental and physical development. Symptoms vary according to the specific type of leukodystrophy, and may be difficult to recognize in the early stages of the disease.

Current research

One source of active (as of 2006) research is The Myelin Project

The Myelin Project

The Myelin Project is an international scientific research organization aimed at accelerating clinical and translational research focused on myelin repair and to regenerate the nerve's myelin sheath, — a process called remyelination — destroyed in a host of diseases such as multiple...

. In addition, many research groups are studying the cellular processes of myelination, which may provide insights into leukodystrophy.

Public awareness

The official color of Leukodystrophies awareness is navy blue.
http://www.stennisfoundation.org/web/

External links

• This article incorporates public domain text from the National Institute of Neurological Disorders and Stroke.