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Hereditary sensory neuropathy type 1 is a condition characterized by nerve abnormalities in the legs and feet (peripheral neuropathy). Many people with this condition have tingling, weakness, and a reduced ability to feel pain and sense hot and cold. Some affected individuals do not lose sensation, but instead feel shooting pains in their legs and feet. As the disorder progresses, the sensory abnormalities can affect the hands, arms, shoulders, and abdomen. Affected individuals may also experience muscle wasting and weakness as they get older, but this varies widely within families.
Affected individuals typically get open sores (ulcers) on their feet or hands or infections of the soft tissue of the fingertips (whitlows) that are slow to heal. Because affected individuals cannot feel the pain of these sores, they may not seek treatment right away. Without treatment, the ulcers can become infected and may require amputation of the surrounding area.
Rarely, people with hereditary sensory neuropathy type 1 will develop hearing loss caused by abnormalities of the inner ear (sensorineural hearing loss).
The signs and symptoms of hereditary sensory neuropathy type 1 typically appear during a person's teens or twenties. While the features of this disorder tend to worsen over time, affected individuals have a normal life expectancy if signs and symptoms are properly treated.
Hereditary sensory neuropathy type 1 is a rare condition, although its exact prevalence is unknown.
Mutations in the SPTLC1 gene cause hereditary sensory neuropathy type 1. The SPTLC1 gene provides instructions for making one part (subunit) of an enzyme called serine palmitoyltransferase (SPT). The SPT enzyme is involved in making certain fats called sphingolipids. Sphingolipids are important components of cell membranes and play a role in many cell functions.
SPTLC1 gene mutations reduce the amount of SPTLC1 subunit that is produced and result in an SPT enzyme with decreased function. A lack of functional SPT enzyme leads to a decrease in sphingolipid production and a harmful buildup of certain byproducts. Sphingolipids are found in myelin, which is the covering that protects nerves and promotes the efficient transmission of nerve impulses. A decrease in sphingolipids disrupts the formation of myelin, causing nerve cells to become less efficient and eventually die. When sphingolipids are not made, an accumulation of toxic byproducts can also lead to nerve cell death. This gradual destruction of nerve cells results in loss of sensation and muscle weakness in people with hereditary sensory neuropathy type 1.
Changes in this gene are associated with hereditary sensory neuropathy type 1.
This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder.
In most cases, an affected person has one parent with the condition.
These resources address the diagnosis or management of hereditary sensory neuropathy type 1 and may include treatment providers.
You might also find information on the diagnosis or management of hereditary sensory neuropathy type 1 in Educational resources (http://www.ghr.nlm.nih.gov/condition/hereditary-sensory-neuropathy-type-1/show/Educational+resources) and Patient support (http://www.ghr.nlm.nih.gov/condition/hereditary-sensory-neuropathy-type-1/show/Patient+support).
General information about the diagnosis (http://ghr.nlm.nih.gov/handbook/consult/diagnosis) and management (http://ghr.nlm.nih.gov/handbook/consult/treatment) of genetic conditions is available in the Handbook. Read more about genetic testing (http://ghr.nlm.nih.gov/handbook/testing), particularly the difference between clinical tests and research tests (http://ghr.nlm.nih.gov/handbook/testing/researchtesting).
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You may find the following resources about hereditary sensory neuropathy type 1 helpful. These materials are written for the general public.
You may also be interested in these resources, which are designed for healthcare professionals and researchers.
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Ask the Genetic and Rare Diseases Information Center (http://rarediseases.info.nih.gov/GARD/).
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You may find definitions for these and many other terms in the Genetics Home Reference Glossary (http://www.ghr.nlm.nih.gov/glossary).
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