Giant axonal neuropathy is a rare,

autosomal An autosome is any chromosome that is not a sex chromosome. The members of an autosome pair in a diploid cell have the same morphology, unlike those in allosomal (sex chromosome) pairs, which may have different structures. The DNA in autosom ...

recessive In genetics, dominance is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome. The first variant is termed dominant and t ...

neurological disorder that causes disorganization of

neurofilament Neurofilaments (NF) are classed as type IV intermediate filaments found in the cytoplasm of neurons. They are protein polymers measuring 10 nm in diameter and many micrometers in length. Together with microtubules (~25 nm) and mi ...

s. Neurofilaments form a structural framework that helps to define the shape and size of

neuron A neuron, neurone, or nerve cell is an electrically excitable cell that communicates with other cells via specialized connections called synapses. The neuron is the main component of nervous tissue in all animals except sponges and placozoa. ...

s and are essential for normal nerve function. A distinguishing feature is its association with kinky, or curly, hair; in such cases it has been called Giant axonal neuropathy with curly hair.

Genetics

Giant axonal neuropathy results from

mutation In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA replication, DNA or viral repl ...

s in the ''GAN''

gene In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a b ...

, which codes for the

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...

gigaxonin. This alters the shape of the protein, changing how it interacts with other proteins when organizing the structure of the

. Neurons affected by the altered protein accumulate excess neurofilaments in the

axon An axon (from Greek ἄξων ''áxōn'', axis), or nerve fiber (or nerve fibre: see spelling differences), is a long, slender projection of a nerve cell, or neuron, in vertebrates, that typically conducts electrical impulses known as action p ...

, the long extension from the

nerve cell A neuron, neurone, or nerve cell is an electrically excitable cell that communicates with other cells via specialized connections called synapses. The neuron is the main component of nervous tissue in all animals except sponges and placozoa. No ...

that transmits its signal to other nerve cells and to muscles. These enlarged or 'giant' axons cannot transmit signals properly, and eventually deteriorate, resulting in the range of neurological anomalies associated with the disorder. This disease is an autosomal recessive disorder, which means the defective gene is located on an autosome, and both parents must have one copy of the defective gene in order to have a child born with the disorder. The parents of a child with an autosomal recessive disorder are carriers, but are usually not affected by the disorder.

Diagnosis

Giant axonal neuropathy usually appears in infancy or early childhood, and is progressive. Early signs of the disorder often present in the peripheral

nervous system In biology, the nervous system is the highly complex part of an animal that coordinates its actions and sensory information by transmitting signals to and from different parts of its body. The nervous system detects environmental changes ...

, causing individuals with this disorder to have problems walking. Later, normal sensation, coordination, strength, and reflexes become affected. Hearing or vision problems may also occur. Abnormally kinky hair is characteristic of giant axonal neuropathy, appearing in almost all cases. As the disorder progresses,

central nervous system The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all p ...

becomes involved, which may cause a gradual decline in mental function, loss of control of body movement, and

seizure An epileptic seizure, informally known as a seizure, is a period of symptoms due to abnormally excessive or synchronous neuronal activity in the brain. Outward effects vary from uncontrolled shaking movements involving much of the body with l ...

Treatment

References

* ''This article may incorporate some public domain text fro
The U.S. National Library of Medicine
'

External links

*
GeneReview/NIH/UW entry on Giant Axonal Neuropathy
{{Cytoskeletal defects Autosomal recessive disorders Rare diseases Neurological disorders Cytoskeletal defects

Genetics

Diagnosis

Treatment

See also

References

External links