National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

Hereditary neuropathy with liability to pressure palsies


Other Names:
HNPP; Polyneuropathy, familial recurrent; Tomaculous neuropathy
Categories:
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]
Last updated: 8/7/2018

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.

Showing of 12 |
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
Showing of 12 |
Last updated: 7/1/2020
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]  
Last updated: 8/7/2018
Hereditary neuropathy with liability to pressure palsies (HNPP) is inherited in an autosomal dominant manner. This means that having a deletion or change (mutation) in only one copy of the responsible gene in each cell is enough to cause features of the disorder. There is nothing that either parent can do, before or during a pregnancy, to cause a child to have HNPP.

In some cases, a person with HNPP inherits the deletion or mutation from a parent with HNPP. In other cases, HNPP occurs for the first time in a person with no family history of the disorder. When a person with HNPP has children, each child has a 50% (1 in 2) chance to have HNPP.[1][2]
Last updated: 8/7/2018

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.
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]
Last updated: 8/7/2018

If you need medical advice, you can look for doctors or other healthcare professionals who have experience with this disease. You may find these specialists through advocacy organizations, clinical trials, or articles published in medical journals. You may also want to contact a university or tertiary medical center in your area, because these centers tend to see more complex cases and have the latest technology and treatments.

If you can’t find a specialist in your local area, try contacting national or international specialists. They may be able to refer you to someone they know through conferences or research efforts. Some specialists may be willing to consult with you or your local doctors over the phone or by email if you can't travel to them for care.

You can find more tips in our guide, How to Find a Disease Specialist. We also encourage you to explore the rest of this page to find resources that can help you find specialists.

Healthcare Resources

Related diseases are conditions that have similar signs and symptoms. A health care provider may consider these conditions in the table below when making a diagnosis. Please note that the table may not include all the possible conditions related to this disease.

Conditions with similar signs and symptoms from Orphanet
Differential diagnosis includes both compression induced mononeuropathies and generalized polyneuropathies. Neuralgic amyotrophy (see this term) can sometimes be mistaken for HNPP.
Visit the Orphanet disease page for more information.

Research helps us better understand diseases and can lead to advances in diagnosis and treatment. This section provides resources to help you learn about medical research and ways to get involved.

Clinical Research Resources

  • ClinicalTrials.gov lists trials that are related to Hereditary neuropathy with liability to pressure palsies. Click on the link to go to ClinicalTrials.gov to read descriptions of these studies.

    Please note: Studies listed on the ClinicalTrials.gov website are listed for informational purposes only; being listed does not reflect an endorsement by GARD or the NIH. We strongly recommend that you talk with a trusted healthcare provider before choosing to participate in any clinical study.
  • Orphanet lists European clinical trials, research studies, and patient registries enrolling people with this condition. 

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

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.

Questions sent to GARD may be posted here if the information could be helpful to others. We remove all identifying information when posting a question to protect your privacy. If you do not want your question posted, please let us know.

  1. Hereditary neuropathy with liability to pressure palsies. Genetics Home Reference. July, 2016; http://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; http://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.