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Hereditary liability to pressure palsies(HNPP)

MedGen UID:
Concept ID:
Disease or Syndrome
Synonyms: Hereditary Neuropathy with Liability to Pressure Palsies; Hereditary neuropathy with liability to pressure palsy; HNPP; Polyneuropathy, familial recurrent; Tomaculous neuropathy
SNOMED CT: Hereditary liability to pressure palsies (230558006); Tomaculous neuropathy (230558006)
Modes of inheritance:
Autosomal dominant inheritance
MedGen UID:
Concept ID:
Intellectual Product
Source: Orphanet
A mode of inheritance that is observed for traits related to a gene encoded on one of the autosomes (i.e., the human chromosomes 1-22) in which a trait manifests in heterozygotes. In the context of medical genetics, an autosomal dominant disorder is caused when a single copy of the mutant allele is present. Males and females are affected equally, and can both transmit the disorder with a risk of 50% for each child of inheriting the mutant allele.
Gene (location): PMP22 (17p12)
Monarch Initiative: MONDO:0008087
OMIM®: 162500
Orphanet: ORPHA640

Disease characteristics

Hereditary neuropathy with liability to pressure palsies (HNPP) is characterized by recurrent acute sensory and motor neuropathy in a single or multiple nerves. The most common initial manifestation is the acute onset of a non-painful focal sensory and motor neuropathy in a single nerve (mononeuropathy). The first attack usually occurs in the second or third decade but earlier onset is possible. Neuropathic pain is increasingly recognized as a common manifestation. Recovery from acute neuropathy is usually complete; when recovery is not complete, the resulting disability is mild. Some affected individuals also demonstrate a mild-to-moderate peripheral neuropathy. [from GeneReviews]
Nicolas Chrestian   view full author information

Additional description

From MedlinePlus Genetics
Hereditary neuropathy with liability to pressure palsies is a disorder that affects peripheral nerves. These nerves connect the brain and spinal cord to muscles and sensory cells that detect touch, pain, and temperature. In people with this disorder, the peripheral nerves are unusually sensitive to pressure, such as the pressure that occurs when carrying heavy grocery bags, leaning on an elbow, or sitting without changing position, particularly with crossed legs. These activities would not normally cause sensation problems in people without the disorder.

Hereditary neuropathy with liability to pressure palsies is characterized by recurrent episodes of numbness, tingling, and loss of muscle function (palsy) in the region associated with the affected nerve, usually an arm, hand, leg, or foot. An episode can last from several minutes to several months, but recovery is usually complete. Repeated incidents, however, can cause permanent muscle weakness or loss of sensation. This disorder is also associated with pain in the limbs, especially the hands.

A pressure palsy episode results from pressure on a single nerve, and any peripheral nerve can be affected. Although episodes often recur, they can affect different nerves. The most common problem sites involve nerves in the wrists, elbows, and knees. The fingers, shoulders, hands, feet, and scalp can also be affected. Many people with this disorder experience carpal tunnel syndrome, which occurs when a nerve in the wrist (the median nerve) is involved. Carpal tunnel syndrome is characterized by numbness, tingling, and weakness in the hand and fingers. An episode in the hand may affect fine motor activities such as writing, opening jars, and fastening buttons. An episode of nerve compression in the knee can lead to a condition called foot drop, which makes walking, climbing stairs, or driving difficult or impossible.

The symptoms of hereditary neuropathy with liability to pressure palsies usually begin during adolescence or early adulthood but may develop anytime from childhood to late adulthood. Symptoms vary in severity; many people never realize they have the disorder, while some people experience prolonged disability. Hereditary neuropathy with liability to pressure palsies does not affect life expectancy.  https://medlineplus.gov/genetics/condition/hereditary-neuropathy-with-liability-to-pressure-palsies

Clinical features

From HPO
Hand muscle weakness
MedGen UID:
Concept ID:
Reduced strength of the musculature of the hand.
MedGen UID:
Concept ID:
Decreased ability to perceive touch.
Peripheral neuropathy
MedGen UID:
Concept ID:
Disease or Syndrome
Peripheral neuropathy is a general term for any disorder of the peripheral nervous system. The main clinical features used to classify peripheral neuropathy are distribution, type (mainly demyelinating versus mainly axonal), duration, and course.
Hand paresthesia
MedGen UID:
Concept ID:
Sign or Symptom
Tingling (often refered to as a pins and needles feeling) and numbness in the hand.
MedGen UID:
Concept ID:
Reduction of neurologic reflexes such as the knee-jerk reaction.
Froment sign
MedGen UID:
Concept ID:
Sign or Symptom
An abnormal result of a physical examination of the the hand that tests for palsy of the ulnar nerve. This nerve innervates the adductor pollicis and interossei muscles and thereby enables adduction of the thumb and extension of the interphalangeal joint. An abnormal result consists in reduced functionality and muscular weakness in the pinch grip between the thumb and index finger of the affected hand as the patient attempts to pinch a piece of paper that the examiner tries to pull away. The flexor pollicis longus muscle tries to compensate for the weakness by flexing the tip of the thumb at the interphalangeal joint.
Segmental peripheral demyelination/remyelination
MedGen UID:
Concept ID:
A segmental pattern of demyelination and regeneration (remyelination) affecting peripheral nerves.
Decreased motor nerve conduction velocity
MedGen UID:
Concept ID:
A type of decreased nerve conduction velocity that affects the motor neuron.
Muscle weakness
MedGen UID:
Concept ID:
Reduced strength of muscles.
Vocal cord paralysis
MedGen UID:
Concept ID:
Disease or Syndrome
A loss of the ability to move the vocal folds.

Term Hierarchy

CClinical test,  RResearch test,  OOMIM,  GGeneReviews,  VClinVar  
  • CROGVHereditary liability to pressure palsies
Follow this link to review classifications for Hereditary liability to pressure palsies in Orphanet.

Professional guidelines


Saporta AS, Sottile SL, Miller LJ, Feely SM, Siskind CE, Shy ME
Ann Neurol 2011 Jan;69(1):22-33. doi: 10.1002/ana.22166. PMID: 21280073Free PMC Article
Chance PF
Suppl Clin Neurophysiol 2004;57:228-42. doi: 10.1016/s1567-424x(09)70360-5. PMID: 16106622
Pareyson D
Neurol Sci 2004 Jun;25(2):72-82. doi: 10.1007/s10072-004-0233-4. PMID: 15221625


Aretz S, Rautenstrauss B, Timmerman V
Eur J Hum Genet 2010 Sep;18(9) Epub 2010 May 26 doi: 10.1038/ejhg.2010.75. PMID: 20512157Free PMC Article

Recent clinical studies


Shahrizaila N, Samulong S, Tey S, Suan LC, Meng LK, Goh KJ, Ahmad-Annuar A
Muscle Nerve 2014 Feb;49(2):198-201. Epub 2013 Oct 4 doi: 10.1002/mus.23892. PMID: 23649551
Jankelowitz SK, Burke D
J Neurol Neurosurg Psychiatry 2013 Jul;84(7):806-12. Epub 2013 Feb 16 doi: 10.1136/jnnp-2012-304576. PMID: 23418209
Ouvrier RA, Nicholson GA
Brain Dev 1995;17 Suppl:31-8. PMID: 8882569


Shahrizaila N, Samulong S, Tey S, Suan LC, Meng LK, Goh KJ, Ahmad-Annuar A
Muscle Nerve 2014 Feb;49(2):198-201. Epub 2013 Oct 4 doi: 10.1002/mus.23892. PMID: 23649551
Sessa M, Nemni R, Quattrini A, Del Carro U, Wrabetz L, Canal N
J Med Genet 1997 Nov;34(11):889-92. doi: 10.1136/jmg.34.11.889. PMID: 9391880Free PMC Article
Harding AE
Baillieres Clin Neurol 1995 Nov;4(3):383-400. PMID: 8599717

Clinical prediction guides

Sessa M, Nemni R, Quattrini A, Del Carro U, Wrabetz L, Canal N
J Med Genet 1997 Nov;34(11):889-92. doi: 10.1136/jmg.34.11.889. PMID: 9391880Free PMC Article

Supplemental Content

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    Clinical resources

    Practice guidelines

    • PubMed
      See practice and clinical guidelines in PubMed. The search results may include broader topics and may not capture all published guidelines. See the FAQ for details.


    • EuroGenetest, 2010
      Clinical utility gene card for: HMSN/HNPP HMSN types 1, 2, 3, 6 (CMT1,2,4, DSN, CHN, GAN, CCFDN, HNA); HNPP

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