Hereditary neuropathy with pressure palsies (HNPP)

Original Editor - Ravi Kumar

Top Contributors - Ravi Kumar  

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Introduction

Hereditary Neuropathy with Pressure Palsies (HNPP) is a rare type of peripheral neuropathy that affects the peripheral nerves. It is inherited in an autosomal dominant manner meaning individuals have a 50% chance of passing it on to their children. People with HNPP have a higher risk of developing nerve damage when their nerves are exposed to mild pressure or trauma, such as crossing the legs, leaning on the elbows, or wearing tight shoes. This can cause episodes of numbness, tingling, pain, and weakness in the affected areas, which usually last from minutes to months. These episodes are called pressure palsieshb

The cause of HNPP is a mutation in the peripheral myelin protein 22 (PMP22) gene, which is responsible for producing a protein called PMP22. This protein plays a crucial role in the formation and maintenance of myelin, the protective covering around nerve fibers. Unfortunately in HNPP the mutation in the PMP22 gene leads to abnormalities in myelin structure and function resulting in nerve dysfunction.

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Symptoms of HNPP include

• Fatigue
• Generalized weakness
• Muscle cramps
• Pain in the muscles or bones
• Lower back pain

Etiology

The etiology of hereditary neuropathy with vulnerability to pressure palsies is predominantly attributed to haploinsufficiency resulting from the deletion of a single allele of the PMP22 gene. The observed outcome leads to a decrease in the production of PMP22 protein. Additionally, several mutations in the PMP22 gene can result in a decrease in the production of the PMP22 protein, hence contributing to the manifestation of the illness.

The PMP22 protein is an essential constituent of myelin, a protective material that envelops nerves and facilitates the effective conduction of nerve impulses. According to existing research, there is evidence to suggest that the PMP22 protein plays a significant role in safeguarding nerves against physical pressure, hence facilitating the restoration of their structural integrity subsequent to compression. The phenomenon of a limb "falling asleep" can be attributed to the interruption of nerve communication caused by compression. The capacity of nerves to undergo recuperation from routine, everyday compression, such as prolonged periods of sitting, serves to prevent a perpetual decline in limb sensation.

The precise understanding of the ramifications associated with mutations in the PMP22 gene remains limited. The observed insufficiency of PMP22 protein seems to hinder the nerves' capacity to recuperate from compression, resulting in impaired transmission of nerve impulses. This, in turn, gives rise to the manifestations and indications associated with hereditary neuropathy with predisposition to pressure palsies.

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