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PRNP

PRNP

Reviewed January 2014

What is the official name of the PRNP gene?

The official name of this gene is “prion protein.”

PRNP is the gene's official symbol. The PRNP gene is also known by other names, listed below.

Read more about gene names and symbols on the About page.

What is the normal function of the PRNP gene?

The PRNP gene provides instructions for making a protein called prion protein (PrP), which is active in the brain and several other tissues. Although the precise function of this protein is unknown, researchers have proposed roles in several important processes. These include the transport of copper into cells and protection of brain cells (neurons) from injury (neuroprotection). Studies have also suggested a role for PrP in the formation of synapses, which are the junctions between nerve cells (neurons) where cell-to-cell communication occurs.

Different forms of PrP have been identified. The normal version is often designated PrPC to distinguish it from abnormal forms of the protein, which are generally designated PrPSc.

Does the PRNP gene share characteristics with other genes?

The PRNP gene belongs to a family of genes called CD (CD molecules).

A gene family is a group of genes that share important characteristics. Classifying individual genes into families helps researchers describe how genes are related to each other. For more information, see What are gene families? in the Handbook.

How are changes in the PRNP gene related to health conditions?

Huntington disease-like syndrome - caused by mutations in the PRNP gene

A particular type of mutation in the PRNP gene has been found to cause signs and symptoms that resemble those of Huntington disease, including uncontrolled movements, emotional problems, and loss of thinking ability. Researchers have proposed that this condition be called Huntington disease-like 1 (HDL1).

The PRNP mutations associated with HDL1 involve a segment of DNA called an octapeptide repeat. This segment provides instructions for making eight protein building blocks (amino acids) that are linked to form a protein fragment called a peptide. The octapeptide repeat is normally repeated five times in the PRNP gene. In people with HDL1, this segment is repeated eleven or thirteen times. An increase in the size of the octapeptide repeat leads to the production of an abnormally long version of PrP. It is unclear how the abnormal protein damages and ultimately destroys neurons, leading to the characteristic features of HDL1.

prion disease - caused by mutations in the PRNP gene

More than 30 mutations in the PRNP gene have been identified in people with familial forms of prion disease, including Creutzfeldt-Jakob disease (CJD), Gerstmann-Sträussler-Scheinker syndrome (GSS), and fatal familial insomnia (FFI). The major features of these diseases include changes in memory, personality, and behavior; a decline in intellectual function (dementia); and abnormal movements, particularly difficulty with coordinating movements (ataxia). The signs and symptoms worsen over time, ultimately leading to death.

Some of the PRNP gene mutations that cause familial prion disease change single amino acids in PrP. Other mutations insert additional amino acids into the protein or result in an unusually short version of the protein. These changes alter the structure of PrP, leading to the production of an abnormally shaped protein, known as PrPSc, from one copy of the PRNP gene. In a process that is not fully understood, PrPSc can attach (bind) to PrPC and promote its transformation into PrPSc. The abnormal protein builds up in the brain, forming clumps that damage or destroy neurons. The loss of these cells creates microscopic sponge-like holes (vacuoles) in the brain, which leads to the signs and symptoms of prion disease.

Researchers have identified several common variations (polymorphisms) in the PRNP gene that affect single amino acids in PrP. These polymorphisms do not cause prion disease, but they may affect a person's risk of developing these disorders. Studies have focused on the effects of a polymorphism at position 129 of PrP. At this position, people can have either the amino acid methionine (Met) or the amino acid valine (Val). This polymorphism is written as Met129Val or M129V. Because people inherit one copy of the PRNP gene from each parent, at position 129 an individual can receive methionine from both parents (Met/Met), valine from both parents (Val/Val), or methionine from one parent and valine from the other (Met/Val).

The Met129Val polymorphism appears to influence the risk of developing prion disease. Most affected individuals have the same amino acid at position 129 (Met/Met or Val/Val) instead of different amino acids (Met/Val). Having Met/Met at position 129 is also associated with an earlier age of onset and a more rapid worsening of the disease's signs and symptoms.

Wilson disease - course of condition modified by normal variations in the PRNP gene

The Met129Val polymorphism has been reported to influence the onset of Wilson disease, an inherited disorder in which excessive amounts of copper accumulate in the body. Wilson disease is caused by mutations in the ATP7B gene, but studies suggest that symptoms of Wilson disease begin several years later in people who have Met/Met at position 129 in PrP compared with those who have Met/Val or Val/Val. Other research findings indicate that this polymorphism may also affect the type of symptoms that develop in people with Wilson disease. Having Met/Met at position 129 appears to be associated with an increased occurrence of symptoms that affect the nervous system, particularly tremors.

other disorders - associated with the PRNP gene

The Met129Val variation has been associated with differences in performance on long-term memory tasks among healthy young adults. In one study, people who had either Met/Met or Met/Val at position 129 performed better at long-term memory tasks than those who had Val/Val. It is unclear how these differences may be related to memory.

Where is the PRNP gene located?

Cytogenetic Location: 20p13

Molecular Location on chromosome 20: base pairs 4,686,150 to 4,701,587

The PRNP gene is located on the short (p) arm of chromosome 20 at position 13.

The PRNP gene is located on the short (p) arm of chromosome 20 at position 13.

More precisely, the PRNP gene is located from base pair 4,686,150 to base pair 4,701,587 on chromosome 20.

See How do geneticists indicate the location of a gene? in the Handbook.

Where can I find additional information about PRNP?

You and your healthcare professional may find the following resources about PRNP helpful.

You may also be interested in these resources, which are designed for genetics professionals and researchers.

What other names do people use for the PRNP gene or gene products?

  • AltPrP
  • ASCR
  • CD230 antigen
  • CJD
  • GSS
  • MGC26679
  • PRIO_HUMAN
  • prion protein (p27-30) (Creutzfeldt-Jakob disease, Gerstmann-Strausler-Scheinker syndrome, fatal familial insomnia)
  • PRIP
  • PrP
  • PrP27-30
  • PrP33-35C
  • PrPc
  • PrPSc

Where can I find general information about genes?

The Handbook provides basic information about genetics in clear language.

These links provide additional genetics resources that may be useful.

What glossary definitions help with understanding PRNP?

acids ; amino acid ; ataxia ; cell ; dementia ; DNA ; familial ; gene ; inherit ; inherited ; injury ; insomnia ; Met ; methionine ; mutation ; nervous system ; peptide ; polymorphism ; prion ; protease ; protein ; proteinaceous infectious particle ; syndrome ; transformation ; Val ; valine

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.

See also Understanding Medical Terminology.

References (13 links)

 

The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? in the Handbook.

 
Reviewed: January 2014
Published: December 22, 2014