Rare Pulmonology News

Disease Profile

Hereditary neuropathy with liability to pressure palsies

Prevalence
Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.
1-9 / 100 000

3,310 - 29,790

US Estimated

1-9 / 100 000

5,135 - 46,215

Europe Estimated

Age of onset

Childhood

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ICD-10

G60.0

Inheritance

Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease

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Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype

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X-linked
dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.

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X-linked
recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder

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Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.

Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.

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Not applicable

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Other names (AKA)

HNPP; Polyneuropathy, familial recurrent; Tomaculous neuropathy

Categories

Congenital and Genetic Diseases; Nervous System Diseases

Summary

Hereditary neuropathy with liability to pressure palsies (HNPP) is a disorder that affects peripheral nerves, causing the nerves to be highly sensitive to pressure. Symptoms usually begin during adolescence or early adulthood but may develop anytime from childhood to late adulthood. Symptoms vary in severity. While some people never realize they have the disorder, others experience prolonged disability. The most common problem sites involve nerves in the wrists, elbows, and knees; however, the fingers, shoulders, hands, feet, and scalp can also be affected. Symptoms associated with HNPP occur in episodes, due to pressure on any single peripheral nerve. Symptoms may include numbness, tingling, and/or loss of muscle function (palsy), pain in the limbs (especially the hands), carpal tunnel syndrome (impairing the ability to use the fingers, hands, and wrists), and foot drop (making it hard or impossible to walk, climb stairs, or drive). Some people experience fatigue, generalized weakness, muscle cramps, pain in the muscles or bones, or lower back pain. An episode of symptoms associated with HNPP can last from several minutes to days or even months. Most people completely recover after an episode, but repeated episodes can cause permanent muscle weakness or loss of sensation.[1][2][3][4][5]

HNPP is most often caused by the loss of one copy (a deletion) of the PMP22 gene, but it may also be cause by a mutation within this gene. It is inherited in an autosomal dominant manner.[1][2][3] The diagnosis is made based on the symptoms present, electrodiagnostic testing, and genetic testing.[6] HNPP is thought to be underdiagnosed, and it may be misdiagnosed as another disorder such as Charcot-Marie Tooth disease.[4]

There is currently no standard medical treatment for HNPP. Management generally involves strategies to avoid or modify positions (such as leaning on the elbows) and activities that cause symptoms, and using splints or pads on the wrists or arms to avoid pressure on the nerves.[2][4][6] An ankle-foot orthosis may be needed permanently for those with a residual foot drop.[2] Management of pain may include over-the-counter pain medicines and/or prescription drugs used for peripheral neuropathy.[4] Special work or school accommodations may be necessary.[5] While the long-term outlook (prognosis) regarding quality of life depends on the frequency and severity of episodes and whether pain and disability persist, HNPP does not affect life expectancy.[1]

Symptoms

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

Medical Terms Other Names
Learn More:
HPO ID
80%-99% of people have these symptoms
Decreased motor nerve conduction velocity
0003431
30%-79% of people have these symptoms
Paresthesia
Pins and needles feeling
Tingling

[ more ]

0003401
Scoliosis
0002650
5%-29% of people have these symptoms
Cranial nerve paralysis
0006824
Hyporeflexia
Decreased reflex response
Decreased reflexes

[ more ]

0001265
Pes cavus
High-arched foot
0001761
Respiratory insufficiency
Respiratory impairment
0002093
Vocal cord paralysis
Inability to move vocal cords
0001605
Percent of people who have these symptoms is not available through HPO
Autosomal dominant inheritance
0000006
Muscle weakness
Muscular weakness
0001324
Peripheral neuropathy
0009830
Segmental peripheral demyelination/remyelination
0003481

Cause

Hereditary neuropathy with liability to pressure palsies is caused by mutations in the PMP22 gene. The condition results when one gene is either missing or altered. While not completely understood, it is believed that mutations in the PMP22 gene affect myelin, the protective substance that covers nerve cells. As a result of these mutations, some of the protective myelin which covers the nerves becomes unstable, leading to the increased sensitivity to pressure on the nerves.[1]

Diagnosis

Making a diagnosis for a genetic or rare disease can often be challenging. Healthcare professionals typically look at a person’s medical history, symptoms, physical exam, and laboratory test results in order to make a diagnosis. The following resources provide information relating to diagnosis and testing for this condition. If you have questions about getting a diagnosis, you should contact a healthcare professional.

Testing Resources

  • The Genetic Testing Registry (GTR) provides information about the genetic tests for this condition. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.
  • Orphanet lists international laboratories offering diagnostic testing for this condition.

    Treatment

    There is no specific treatment for hereditary neuropathy with liability to pressure palsies (HNPP). Management is based on each person's symptoms and severity. Some people use braces, such as a wrist splint, or ankle-foot orthosis (for foot drop). Protective pads worn at the elbows or knees may prevent pressure and trauma to local nerves. In general, people with HNPP should try to avoid positions and activities that cause pressure on the nerves, such as prolonged sitting (particularly with the legs crossed), leaning on the elbows, occupations requiring repetitive movements of the wrist, and tying shoes too tightly.[2][4][6] For mild pain, over-the-counter pain medicines may be used. For more severe pain, prescription drugs used for peripheral neuropathy may be used.[4]

    Organizations

    Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

    Organizations Supporting this Disease

      Organizations Providing General Support

        Learn more

        These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

        Where to Start

          In-Depth Information

          • GeneReviews provides current, expert-authored, peer-reviewed, full-text articles describing the application of genetic testing to the diagnosis, management, and genetic counseling of patients with specific inherited conditions.
          • The Merck Manual for health care professionals provides information on Hereditary neuropathy with liability to pressure palsies.
          • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
          • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
          • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
          • PubMed is a searchable database of medical literature and lists journal articles that discuss Hereditary neuropathy with liability to pressure palsies. Click on the link to view a sample search on this topic.

            References

            1. Hereditary neuropathy with liability to pressure palsies. Genetics Home Reference. July, 2016; https://ghr.nlm.nih.gov/condition/hereditary-neuropathy-with-liability-to-pressure-palsies.
            2. Bird TD. Hereditary Neuropathy with Liability to Pressure Palsies. GeneReviews. September 25, 2014; https://www.ncbi.nlm.nih.gov/books/NBK1392/.
            3. Hereditary Neuropathy With Liability To Pressure Palsies. Hereditary Neuropathy Foundation. https://www.hnf-cure.org/cmt-hnpp/. Accessed 8/7/2018.
            4. Hereditary Neuropathy With Liability To Pressure Palsies (HNPP). The Foundation for Peripheral Neuropathy. https://www.foundationforpn.org/what-is-peripheral-neuropathy/causes/heredity-disorders/. Accessed 8/7/2018.
            5. Kang PB. Charcot-Marie-Tooth disease: Genetics, clinical features, and diagnosis. UpToDate. Waltham, MA: UpToDate; Jun 12, 2018; https://www.uptodate.com/contents/charcot-marie-tooth-disease-genetics-clinical-features-and-diagnosis.
            6. Rubin M. Hereditary Motor Neuropathy With Liability to Pressure Palsies (HNPP). Merck Manual. July, 2018; https://www.merckmanuals.com/professional/neurologic-disorders/peripheral-nervous-system-and-motor-unit-disorders/hereditary-motor-neuropathy-with-liability-to-pressure-palsies-hnpp#v27841086.

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