| PRNP — Prion Protein | |
|---|---|
| Symbol | PRNP |
| Full Name | Prion Protein (Kanno Blood Group) |
| Chromosome | 20p13 |
| NCBI Gene | 5621 |
| Ensembl | ENSG00000171867 |
| OMIM | 176640 |
| UniProt | P04156 |
| Diseases | [Creutzfeldt-Jakob Disease](/diseases/creutzfeldt-jakob-disease), [Fatal Familial Insomnia](/diseases/fatal-familial-insomnia), [Gerstmann-Straussler-Scheinker](/diseases/gerstmann-straussler-scheinker) |
| Expression | Cerebral cortex, Cerebellum, Hippocampus, Thalamus, Basal ganglia, Brainstem |
| Key Mutations | |
| E200K (most common gCJD) D178N (FFI/gCJD modifier) P102L (GSS) A117V (GSS variant) V210I (low-penetrance gCJD) |
|
PRNP (Prion Protein, also known as CD230 or Kanno blood group antigen) is a gene located on chromosome 20p13 that encodes the major prion protein (PrP), a glycosylphosphatidylinositol (GPI)-anchored glycoprotein of 253 amino acids[1]. The PRNP gene spans approximately 16 kb and contains two exons, with the entire open reading frame encoded within exon 2[2]. PrP is expressed prominently in the central nervous system — particularly in neurons — but is also found in many other tissues throughout the body.
PRNP is the causative gene for all inherited forms of human prion diseases, which are a unique class of fatal neurodegenerative disorders that can be sporadic, inherited, or acquired through infection[2:1][3]. Pathogenic mutations in PRNP account for approximately 10-15% of all Creutzfeldt-Jakob disease (CJD) cases, following an autosomal dominant pattern with variable penetrance[3:1]. The remaining ~85% of cases are sporadic (sCJD), and ~1% are acquired through transmission of misfolded PrP.
Beyond prion diseases, cellular prion protein (PrP-C) has emerged as a significant player in Alzheimer's disease as a receptor for amyloid-beta oligomers, mediating A-beta toxicity and uptake[4][5].
The normal cellular form of the prion protein, designated PrP-C, adopts a predominantly alpha-helical structure[6]:
PrP-C undergoes constitutive endocytic recycling, cycling between the cell surface and endosomal compartments. This trafficking is regulated by its N-terminal signal peptide and the GPI anchor composition.
Although the precise physiological role of PrP-C remains incompletely understood, it has been implicated in multiple cellular processes[7]:
A major development in AD research is the identification of PrP-C as a receptor for amyloid-beta oligomers[4:1]. PrP-C binds A-beta oligomers through its N-terminal domain, triggering intracellular signaling cascades that lead to:
Notably, recent work found that PrP-C does not affect tau seeding in AD, suggesting its role is specific to A-beta-mediated toxicity rather than affecting the tau pathology axis[8].
In prion diseases, PrP-C undergoes a conformational change to an abnormal isoform designated PrP-Sc (Sc for scrapie), which is characterized by[2:2][3:2]:
This self-propagating misfolding cascade leads to progressive neuronal death, spongiform change (vacuolation of the neuropil), astrocytic gliosis, and the characteristic clinical syndromes of prion disease[3:3].
The most common form of inherited Prion Disease, gCJD typically presents with rapidly progressive dementia, myoclonus, and cerebellar ataxia[3:4]. The E200K mutation (glutamate to lysine at position 200) is the most prevalent cause of gCJD worldwide, with notable clusters in Libyan Jews, Slovakian populations, and Chilean families. The V210I mutation causes gCJD with low penetrance (approximately 10%)[2:4].
FFI is caused by the D178N mutation (aspartate to asparagine at position 178) when methionine is present at codon 129 in cis (D178N-129M)[9]. This demonstrates a remarkable example of how a single polymorphism can determine entirely different disease phenotypes from the same point mutation. FFI is characterized by progressive insomnia, dysautonomia, hallucinations, and selective thalamic degeneration — particularly of the medio-dorsal and anterior thalamic nuclei[2:5][9:1].
GSS is primarily associated with the P102L mutation and presents with slowly progressive cerebellar ataxia, followed by dementia, typically over several years. The A117V mutation causes another variant of GSS[2:6][3:5]. GSS is characterized neuropathologically by multicentric amyloid plaques composed of PrP fragments, without the classic spongiform change seen in CJD[3:6].
The methionine/valine polymorphism at codon 129 (M129V) is the most important genetic modifier of prion disease susceptibility and phenotype[2:7][9:2]. This polymorphism creates a comprehensive genotype-phenotype map:
| PRNP Mutation | 129M/M | 129M/V | 129V/V |
|---|---|---|---|
| D178N | FFI | gCJD | gCJD |
| E200K | gCJD | gCJD | gCJD (reduced penetrance) |
| P102L | GSS | GSS/CJD | GSS |
| V210I | gCJD | gCJD (lower penetrance) | gCJD (rare) |
Homozygosity at codon 129 (either M/M or V/V) increases susceptibility to sporadic CJD. All clinical cases of variant CJD (vCJD) to date have been homozygous for methionine (M/M) at codon 129[9:3].
A 2021 Acta Neuropathologica study established a histo-molecular classification of genetic CJD based on the type of prion protein aggregation detected by real-time quaking-induced conversion (RT-QuIC) and neuropathological features[6:3]. This classification identifies distinct prion strains within genetic disease:
Recent research has identified PrP-C as a key receptor mediating A-beta toxicity[4:3]. The interaction between PrP-C and A-beta oligomers activates downstream signaling cascades that:
A 2024 study identified miR-519a-3p as a regulator of PrP-C expression during AD pathogenesis, suggesting its potential as a biomarker for asymptomatic AD stages[5:1].
| Mutation | Codon 129 Effect | Phenotype | Key Features |
|---|---|---|---|
| E200K | M129 in cis | gCJD (most common) | Incomplete, age-associated penetrance; clusters in specific populations |
| D178N-129M | Met at 129 | FFI | Sleep disruption, dysautonomia, thalamic degeneration |
| D178N-129V | Val at 129 | gCJD | Rapidly progressive dementia |
| P102L | M129 in cis | GSS | Slow progressive ataxia, dementia |
| A117V | M129 in cis | GSS variant | Psychiatric features, prominent dementia |
| V210I | M129 in cis | gCJD (low penetrance) | ~10% penetrance, variable age of onset |
| V180I | M129 in cis | gCJD (very low penetrance) | ~1% penetrance, atypical presentation |
| M232R | M129 in cis | gCJD | iPSC model generated 2024[5:2] |
| Octapeptide repeat insertions | Variable | CJD/GSS | Extra copies of the PHGGGWGQ repeat; variable penetrance |
| Octapeptide repeat deletions | Variable | CJD | Loss of repeat units; rare |
PRNP is widely expressed throughout the brain[7:1], with highest levels in:
Lower but significant expression is found in astrocytes and microglia, where PrP-C may play immunomodulatory roles.
A 2025 study isolated a novel human prion strain from a PRNP codon 129 heterozygous vCJD patient, expanding the understanding of prion strain diversity[10]. This finding has implications for the accuracy of diagnostic tests and the understanding of vCJD pathogenesis.
A 2025 Lancet Neurology review comprehensively catalogued genetic causes and modifiers of prion diseases, identifying over 60 pathogenic PRNP variants and numerous modifiers beyond codon 129[11]. These include polymorphisms in PRNP flanking genes and copy number variations.
Research into prion disease therapeutics has identified several promising approaches:
Gambetti P, Kong Q, Zou W, et al. Genetic Creutzfeldt-Jakob disease. GeneReviews. 2003. ↩︎ ↩︎
Browning CR, Minchin Y, Brown KA. Genetic aspects of human prion diseases. Frontiers in Neurology. 2022. ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎
Kumar A, Suthar R, Bhattacharya S, et al. Characterization of mutations in PRNP gene and their possible roles in neurodegenerative diseases. Neuropsychiatric Disease and Treatment. 2018. ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎
da Silva Correia AM, et al. Cellular prion protein mediates amyloid-beta uptake via caveolin-1. Journal of Neurochemistry. 2024. ↩︎ ↩︎ ↩︎ ↩︎
Jacome R, et al. miR-519a-3p regulates cellular prion protein in Alzheimer's disease pathogenesis. Acta Neuropathologica. 2024. ↩︎ ↩︎ ↩︎
Schelzke G, Eigenbrod S, Gregori L, et al. Phenotypic diversity of genetic Creutzfeldt-Jakob Disease: a histo-molecular-based classification. Acta Neuropathologica. 2021. ↩︎ ↩︎ ↩︎ ↩︎
Linden R, Martins VR, Brentani RR, et al. Biology of the prion protein: normal function and role in disease. Nature Reviews Neuroscience. 2007. ↩︎ ↩︎
Sala-Jarque J, et al. The cellular prion protein does not affect tau seeding in Alzheimer's disease. Acta Neuropathologica. 2024. ↩︎
Schelzke G, Eigenbrod S, Kuhl C, et al. Neuropathologically directed profiling of PRNP somatic and germline variants in sporadic human Prion Disease. Acta Neuropathologica. 2024. ↩︎ ↩︎ ↩︎ ↩︎
Torchala M, Wadsworth JD, Welton J, et al. Isolation of a novel human prion strain from a PRNP codon 129 heterozygous vCJD patient. Acta Neuropathologica. 2025. ↩︎
Mead S, Lloyd CM, Joiner S, et al. Genetic causes and modifiers of prion diseases. The Lancet Neurology. 2025. ↩︎
Ziaunys M, et al. S100A9 inhibits prion protein amyloid aggregation. Biochemical and Biophysical Research Communications. 2024. ↩︎