Prion Protein Gene Research Articles

Prodromal Parkinson disease signs are predicted by a whole-blood inflammatory transcriptional signature in young Pink1−/− rats

BackgroundParkinson disease (PD) is the fastest growing neurodegenerative disease. The molecular pathology of PD in the prodromal phase is poorly understood; as such, there are no specific prognostic or diagnostic tests. A validated Pink1 genetic knockout rat was used to model early-onset and progressive PD. Male Pink1−/− rats exhibit progressive declines in ultrasonic vocalizations as well as hindlimb and forelimb motor deficits by mid-to-late adulthood. Previous RNA-sequencing work identified upregulation of genes involved in disease pathways and inflammation within the brainstem and vocal fold muscle. The purpose of this study was to identify gene pathways within the whole blood of young Pink1−/− rats (3 months of age) and to link gene expression to early acoustical changes. To accomplish this, limb motor testing (open field and cylinder tests) and ultrasonic vocalization data were collected, immediately followed by the collection of whole blood and RNA extraction. Illumina® Total RNA-Seq TruSeq platform was used to profile differential expression of genes. Statistically significant genes were identified and Weighted Gene Co-expression Network Analysis was used to construct co-expression networks and modules from the whole blood gene expression dataset as well as the open field, cylinder, and USV acoustical dataset. ENRICHR was used to identify the top up-regulated biological pathways.ResultsThe data suggest that inflammation and interferon signaling upregulation in the whole blood is present during early PD. We also identified genes involved in the dysregulation of ribosomal protein and RNA processing gene expression as well as prion protein gene expression.ConclusionsThese data identified several potential blood biomarkers and pathways that may be linked to anxiety and vocalization acoustic parameters and are key candidates for future drug-repurposing work and comparison to human datasets.

Single nucleotide polymorphisms (SNPs) in the open reading frame (ORF) of prion protein gene (PRNP) in Nigerian livestock species

BackgroundPrion diseases, also known as transmissible spongiform encephalopathies (TSEs) remain one of the deleterious disorders, which have affected several animal species. Polymorphism of the prion protein (PRNP) gene majorly determines the susceptibility of animals to TSEs. However, only limited studies have examined the variation in PRNP gene in different Nigerian livestock species. Thus, this study aimed to identify the polymorphism of PRNP gene in Nigerian livestock species (including camel, dog, horse, goat, and sheep). We sequenced the open reading frame (ORF) of 65 camels, 31 village dogs and 12 horses from Nigeria and compared with PRNP sequences of 886 individuals retrieved from public databases.ResultsAll the 994 individuals were assigned into 162 haplotypes. The sheep had the highest number of haplotypes (n = 54), and the camel had the lowest (n = 7). Phylogenetic tree further confirmed clustering of Nigerian individuals into their various species. We detected five non-synonymous SNPs of PRNP comprising of G9A, G10A, C11G, G12C, and T669C shared by all Nigerian livestock species and were in Hardy-Weinberg Equilibrium (HWE). The amino acid changes in these five non-synonymous SNP were all “benign” via Polyphen-2 program. Three SNPs G34C, T699C, and C738G occurred only in Nigerian dogs while C16G, G502A, G503A, and C681A in Nigerian horse. In addition, C50T was detected only in goats and sheep.ConclusionOur study serves as the first to simultaneously investigate the polymorphism of PRNP gene in Nigerian livestock species and provides relevant information that could be adopted in programs targeted at breeding for prion diseases resistance.

Integrated transcriptomics uncovers an enhanced association between the prion protein gene expression and vesicle dynamics signatures in glioblastomas

BackgroundGlioblastoma (GBM) is an aggressive brain tumor that exhibits resistance to current treatment, making the identification of novel therapeutic targets essential. In this context, cellular prion protein (PrPC) stands out as a potential candidate for new therapies. Encoded by the PRNP gene, PrPC can present increased expression levels in GBM, impacting cell proliferation, growth, migration, invasion and stemness. Nevertheless, the exact molecular mechanisms through which PRNP/PrPC modulates key aspects of GBM biology remain elusive.MethodsTo elucidate the implications of PRNP/PrPC in the biology of this cancer, we analyzed publicly available RNA sequencing (RNA-seq) data of patient-derived GBMs from four independent studies. First, we ranked samples profiled by bulk RNA-seq as PRNPhigh and PRNPlow and compared their transcriptomic landscape. Then, we analyzed PRNP+ and PRNP- GBM cells profiled by single-cell RNA-seq to further understand the molecular context within which PRNP/PrPC might function in this tumor. We explored an additional proteomics dataset, applying similar comparative approaches, to corroborate our findings.ResultsFunctional profiling revealed that vesicular dynamics signatures are strongly correlated with PRNP/PrPC levels in GBM. We found a panel of 73 genes, enriched in vesicle-related pathways, whose expression levels are increased in PRNPhigh/PRNP+ cells across all RNA-seq datasets. Vesicle-associated genes, ANXA1, RAB31, DSTN and SYPL1, were found to be upregulated in vitro in an in-house collection of patient-derived GBM. Moreover, proteome analysis of patient-derived samples reinforces the findings of enhanced vesicle biogenesis, processing and trafficking in PRNPhigh/PRNP+ GBM cells.ConclusionsTogether, our findings shed light on a novel role for PrPC as a potential modulator of vesicle biology in GBM, which is pivotal for intercellular communication and cancer maintenance. We also introduce GBMdiscovery, a novel user-friendly tool that allows the investigation of specific genes in GBM biology.

Sodium hypochlorite inactivation of human CJD prions.

Prion diseases are transmissible, fatal neurologic diseases of mammals caused by the accumulation of mis-folded, disease associated prion protein (PrPd). Creutzfeldt-Jakob Disease (CJD) is the most common human prion disease and can occur by sporadic onset (sCJD) (~85% of CJD cases), genetic mutations in the prion protein gene (10-15%) or iatrogenic transmission (rare). PrPd is difficult to inactivate and many methods to reduce prion infectivity are dangerous, caustic, expensive, or impractical. Identifying viable and safe methods for decontamination of CJD exposed materials is critically important for medical facilities and research institutions. Previous research has shown that concentrated sodium hypochlorite (bleach) was effective at inactivation of CJD prions derived from brains of mice or guinea pigs. Unfortunately, human prions adapted to rodents may mis-fold differently than in humans, and the rodent adapted prions may not have the same resistance or susceptibility to inactivation present in bona fide CJD prions. To confirm that bleach was efficacious against human sourced CJD prions, we exposed different subtypes of sCJD-infected human brain homogenates to different concentrations of bleach for increasing exposure times. Initial and residual prion seeding activity following inactivation were measured using Real-Time Quaking Induced Conversion. In addition, we tested how passage of human sCJD into either transgenic mice that expressed human prion protein, or transmission of CJD to human cerebral organoids (CO), two common laboratory practices, may affect CJD prions' susceptibility to bleach inactivation. Our results show that bleach is effective against human sourced sCJD prions, and both treatment time and concentration of bleach were important factors for CJD inactivation. CJD derived from human brains, transgenic mouse brains or CO were all susceptible to inactivation with as low as a 10 percent bleach solution with a 30-minute exposure time or a 50 percent bleach solution with as little as a 1-minute exposure time.

Accumulation Area of a Japanese PRNP P102L Variant Associated With Gerstmann-Sträussler-Scheinker Disease: The Ariake PRNP P102L Variant.

The coast of Kyushu Island on Ariake Sea in Japan is known to be an accumulation area for patients with a proline-to-leucine substitution mutation at residue 102 (P102L) of the human prion protein gene (PRNP), which is associated with Gerstmann-Sträussler-Scheinker disease. We designated this geographical distribution as the "Ariake PRNP P102L variant." The purpose of this study was to characterize the clinical features of this variant. We enrolled patients with the PRNP P102L variant who were followed up at the Saga University Hospital from April 2002 to November 2019. The clinical information of patients were obtained from medical records, including clinical histories, brain magnetic resonance imaging (MRI), and electroencephalography (EEG). A brain autopsy was performed on one of the participants. We enrolled 24 patients from 19 family lines, including 12 males. The mean age at symptom onset was 60.6 years (range, 41-77 years). The incidence rate of the Ariake PRNP P102L variant was 3.32/1,000,000 people per year in Saga city. The initial symptoms were ataxia (ataxic gait or dysarthria) in 19 patients (79.2%), cognitive impairment in 3 (12.5%), and leg paresthesia in 2 (8.3%). The median survival time from symptom onset among the 18 fatal cases was 63 months (range, 23-105 months). Brain MRI revealed no localized cerebellar atrophy, but sparse diffusion-weighted imaging abnormalities were detected in 16.7% of the patients. No periodic sharp-wave complexes were identified in EEG. Neuropathological investigations revealed uni- and multicentric prion protein (PrP) plaques in the cerebral cortex, putamen, thalamus, and cerebellum of one patient. Western blot analysis revealed 8-kDa proteinase-K-resistant PrP. This is the first report of the accumulation area of a PRNP P102L variant on the coast of Ariake Sea. The Ariake PRNP P102L variant can be characterized by a relatively long disease duration with sparse abnormalities in brain MRI and EEG relative to previous reports. Detailed interviews to obtain information on the birthplace and the family history of related symptoms are important to diagnosing a PRNP P102L variant.

Genetic characterization of the prion protein gene in camels (Camelus) with comments on the evolutionary history of prion disease in Cetartiodactyla.

Transmissible spongiform encephalopathies (TSEs) are a fatal neurogenerative disease that include Creutzfeldt-Jakob disease in humans, scrapie in sheep and goats, bovine spongiform encephalopathy (BSE), and several others as well as the recently described camel prion disease (CPD). CPD originally was documented in 3.1% of camels examined during an antemortem slaughterhouse inspection in the Ouargla region of Algeria. Of three individuals confirmed for CPD, two were sequenced for the exon 3 of the prion protein gene (PRNP) and were identical to sequences previously reported for Camelus dromedarius. Given that other TSEs, such as BSE, are known to be capable of cross-species transmission and that there is household consumption of meat and milk from Camelus, regulations to ensure camel and human health should be a One Health priority in exporting countries. Although the interspecies transmissibility of CPD currently is unknown, genotypic characterization of Camelus PRNP may be used for predictability of predisposition and potential susceptibility to CPD. Herein, eight breeds of dromedary camels from a previous genetic (mitochondrial DNA and microsatellites) and morphological study were genotyped for PRNP and compared to genotypes from CPD-positive Algerian camels. Sequence data from PRNP indicated that Ethiopian camels possessed 100% sequence identity to CPD-positive camels from Algeria. In addition, the camel PRNP genotype is unique compared to other members of the Orders Cetartiodactyla and Perissodactyla and provides an in-depth phylogenetic analysis of families within Cetartiodactyla and Perissodactyla that was used to infer the evolutionary history of the PRNP gene.

National Prevalence of Caprine Prion Protein Genetic Variability at Codons 146, 211, and 222 in Goat Herds in the United States.

Scrapie is a neurodegenerative disease that impacts sheep and goats, characterized by gradual and progressive changes in neurological function. Recent research shows that the scrapie incubation period is significantly influenced by specific variations in amino acids within the prion protein gene (PRNP). The objective of this study was to estimate the national prevalence of caprine PRNP genetic variability at codons 146, 211, and 222 in goat populations across the United States. A total of 3052 blood, ear tissue, and brain tissue samples were collected from goats from 50 states. The participating states were categorized into four Veterinary Service (VS) district regions. The samples underwent DNA extraction, and the PRNP variants corresponding to codons 146, 211, and 222 were amplified and sequenced. The analysis of PRNP variants, when compared to the PRNP reference sequence, revealed seven alleles in twelve genotypes. The homozygous 146NN, 211RR, and 222QQ alleles, which have been linked to an increased risk of scrapie, were found to be the most prevalent among all the goats. The heterozygous 222QK, 211RQ, 146SD, 146ND, and 146NS alleles and the homozygous 222KK, 146SS, and 146DD alleles, known to be associated with reduced scrapie susceptibility and a prolonged incubation period after experimental challenge, were found in 1.098% (222QK), 2.33% (211RQ), 0.58% (146SD), 3.13% (146ND), 20.68% (146NS), 0.005% (222KK), 3.31% (146SS), and 0.67% (146DD) of goats, respectively. The 222QK allele was found most frequently in goats tested from the east (VS District 1, 1.59%) and southwest (VS District 4, 1.08%) regions, whereas the 211RQ allele was found most often in goats tested from the Midwest (VS District 2, 8.03%) and east (VS District 1, 6.53%) regions. The 146NS allele was found most frequently in goats tested from the northwest (VS District 3, 29.02%) and southwest (VS District 4, 20.69%) regions. Our results showed that the prevalence of less susceptible genotypes at PRNP codon 146 may be sufficient to use genetic susceptibility testing in some herds. This may reduce the number of goats removed as part of a herd clean-up plan and may promote the selective breeding goats for less susceptible alleles in high-risk herds at the national level.

Аnalysis of the imports of Ile de France animals in Bulgaria, 2005-2023

The meat sheep breed Ile-de-France was introduced from France to Bulgaria more than 50 years ago. However, the most imports took place in the recent 20 years and especially after the establishment in 2005 of a breeding association for this breed in Bulgaria. In this study, an attempt to analyse and review the imports from France in the last 18 years was made. It was based on the data about the imported animals provided by the Association for breeding of Ile-de-France sheep in Bulgaria. These animals were selected for import not only on the quality of their parents, but also on their genetic predisposal to classical Scrapie. As a result, most of the animals with known prion protein gene genotypes were of the preferred, low risk one. Within the parents, for which data was available, 34% of the sires were ranked as improvers of growth qualities, and 45% of the dams as mothers of sires. The animals were raised in similar climatic conditions in both countries. The animal with most progeny in the herdbook was also imported one, having 163 records as a sire. The continuous import of low risk genotype animals should have positive impact on the resistance of the local population against Scrapie. As there are also Ile-de-France animals raised in Bulgaria, it might be beneficial to monitor the genetic diversity of prion protein gene in the local population.

Sequence Analysis of Prion Protein Gene in Bhagnari Cattle Breed from the Hottest Region of Sibi, Balochistan, Pakistan

Prion diseases are a type of neurodegenerative disorder caused by the transmission of specific pathogens containing prion proteins. Due to the unique structural characteristics of Prion proteins (PrP), which differ from other types of proteins, the extended incubation period observed in the transmission of specific Prions can be attributed to these differences, at least in part. Prions are found in several other mammals and animals. Prions are unique among false protein folding abnormalities because these are infections and contain various strains of contagious agents associated with a unique in vivo phenotype. They can be acquired either by inheritance or sporadically. There are two types: classical and typical BSP. The objective of this study was to observe the Bhagnari cattle breed of Balochistan, Pakistan, and compare the PrP gene sequence of the Bhagnari with other reported sequences from Pakistan and other parts of the world. This research collected 40 Bhagnari cattle blood samples from Tali, Bhag Nari, and Sibi district areas. DNA extraction of each sample was performed by inorganic method, and then DNA amplification and sequencing of PRNP Gene was performed. The results of this research work showed different polymorphic variations (SNPs) in 16 samples. In this study, while mutations causing prion diseases in cattle were detected in Italian and German breeds, none were identified in the PRNP gene of the cattle population investigated, despite its association with neurological disorders.

The first report of polymorphisms of the prion protein gene (PRNP) in Pekin ducks (Anas platyrhynchos domestica).

Prion diseases have been extensively reported in various mammalian species and are caused by a pathogenic prion protein (PrPSc), which is a misfolded version of cellular prion protein (PrPC). Notably, no cases of prion disease have been reported in birds. Single nucleotide polymorphisms (SNPs) of the prion protein gene (PRNP) that encodes PrP have been associated with susceptibility to prion diseases in several species. However, no studies on PRNP polymorphisms in domestic ducks have been reported thus far. To investigate PRNP polymorphisms in domestic ducks, we isolated genomic DNA from 214 Pekin duck samples and sequenced the coding region of the Pekin duck PRNP gene. We analyzed genotype, allele, and haplotype distributions and linkage disequilibrium (LD) among the SNPs of the Pekin duck PRNP gene. In addition, we evaluated the effects of the one non-synonymous SNP on the function and structure of PrP using the PROVEAN, PANTHER, SNPs & GO, SODA, and AMYCO in silico prediction programs. We found five novel SNPs, c.441 T > C, c.495 T > C, c.582A > G, c.710C > T(P237L), and c.729C > T, in the ORF region of the PRNP gene in 214 Pekin duck samples. We observed strong LD between c.441 T > C and c.582A > G (0.479), and interestingly, the link between c.495 T > C and c.729C > T was in perfect LD, with an r2 value of 1.0. In addition, we identified the five major haplotype frequencies: TTACC, CTGCC, CTACC, CCGCT, and CTATC. Furthermore, we found that the non-synonymous SNP, c.710C > T (P237L), had no detrimental effects on the function or structure of Pekin duck PrP. However, the non-synonymous SNP had deleterious effects on the aggregation propensity and solubility of Pekin duck PrP compared with wildtype Pekin duck PrP. To the best of our knowledge, this study is the first report on the genetic characteristics of PRNP SNPs in Pekin ducks.

Unraveling the Molecular Mechanism of Prion Disease: insights from $\alpha$2 Area Mutations in Human Prion Protein

Abstract Prion diseases are a class of fatal neurodegenerative diseases caused by misfolded prion proteins. The main reason is that pathogenic prion protein has a strong tendency to aggregate, which easily induces the damage of central nervous system. Point mutations in the human prion protein gene can cause prion diseases such as Creutzfeldt-Jakob, Gerstmann’s syndrome. To understand the mechanism of mutation-induced prion protein aggregation, the mutants in an aqueous solution were studied by molecular dynamics simulations, including the wild type, V180I, H187R and a double point mutation which is associated with CJD and GSS. After running simulations for 500 ns, the results show that these three mutations have different effects on the kinetic properties of PrP. The high fluctuations around the N-terminal residues of helix 2 in the V180I variant lead to a decrease in hydrogen bonding on helix 2, while an increase in the number of hydrogen bonds between the folded regions promotes the generation of β-sheet. Meanwhile, partial deletion of salt bridges in the H187R and Double mutants allows the sub-structural domains of the prion protein to separate, which would accelerate the conversion from PrPC to PrPSc. A similar trend is observed in both SASA and Rg for all three mutations, indicating that the conformational space is reduced and the structure is compact.

Validation of the Medical Research Council prion disease rating scale in France.

The development of assessment tools other than survival time is necessary to conduct therapeutic trials in prion diseases (also known as subacute transmissible encephalopathies). The Medical Research Council Prion Disease Rating Scale published by Thompson et al. (The Medical Research Council prion disease rating scale: A new outcome measure for prion disease therapeutic trials developed and validated using systematic observational studies. Brain. 2013; 136: 1116-27.) is the first attempt at a specific evaluation of prion diseases to avoid the floor effect seen in other scales. Validation of this scale in other countries is essential because, given the rarity of these diseases, therapeutic trials are likely to be multi-centre and international. After translation into French, we assessed by phone 173 cases classified as sporadic Creutzfeldt-Jakob disease out of 852 patients notified to the French national surveillance network between November 2014 and May 2021. Data showed that the natural history of the disease is similar in the UK and France. Patients who have a heterozygous genotype at codon 129 of the prion protein gene have a slower decline than homozygous patients. In rapidly progressing patients, death occurs shortly after reaching a low score or after a 'pre-terminal plateau' at a very low score. The similarities of disease progression profile observed in France and the UK with somewhat different surveillance systems and by distinct procedures highlight the robustness of the Medical Research Council Prion Disease Rating Scale that can be thus used to define primary endpoints of future trials at the international level.

Characterization of the First Case of Classical Scrapie in a Sheep in Tunisia

Classical scrapie is a contagious prion disease of sheep and goats. It is endemic in many countries in Europe, North America, and Asia. In Africa, imported scrapie cases have been described in South Africa and Kenia in the past. More recently, several cases have been reported from different regions of Libya, based on clinical signs and histological lesions. Here, we report the results of thorough investigations carried out on a suspect case of scrapie in a 6-year-old Barbarine sheep, born, and bred in Tunisia, showing behavioral changes, weight loss, itching, skin lesions, wool loss, and motor incoordination. Histopathology and immunohistochemistry revealed spongiform change in several brain areas with associated pathological prion protein deposition. Western blotting confirmed the diagnosis and showed a classical scrapie-like molecular pattern of PrPres, different from atypical scrapie and bovine spongiform encephalopathy (BSE) in small ruminants. Sequence analysis of the prion protein gene showed that the animal carried the ARQ/ARQ genotype, one of the most susceptible to classical scrapie. The inoculation of sheep brain homogenate in a susceptible rodent model proved the experimental transmissibility of the disease. These results demonstrate the circulation of classical scrapie in Tunisia and confirm its presence in North Africa, indicating the need to improve epidemiological surveillance and diagnostic capacity for prion diseases in the region.

Novel polymorphisms in the prion protein gene (PRNP) and stability of the resultant prion protein in different horse breeds

Prion diseases are fatal neurodegenerative disorders in which the main pathogenic event is the conversion of the cellular prion protein (PrPC) into an abnormal and misfolded isoform known as PrPSc. Most prion diseases and their susceptibility and pathogenesis are mainly modulated by the PRNP gene that codes for PrP. Mutations and polymorphisms in the PRNP gene can alter PrPC amino acid sequence, leading to a change in transmission efficiency depending on the place where it occurs. Horses are animals that are considered to be highly resistant to prions. Several studies have attempted to identify polymorphisms in the PRNP gene that explain the reason for this high resistance. In this study, we have analysed 207 horses from 20 different breeds, discovering 3 novel PRNP polymorphisms. By using computer programmes such as PolyPhen-2, PROVEAN, PANTHER, Meta-SNP and PredictSNP, we have predicted the possible impact that these new polymorphisms would have on the horse prion protein. In addition, we measured the propensity for amyloid aggregation using AMYCO and analysed the lack of hydrogen bridges that these changes would entail together with their electrostatic potentials using Swiss-PdbViewer software, showing that an increased amyloid propensity could be due to changes at the level of electrostatic potentials.

NGS study in a sicilian case series with a genetic diagnosis for Gerstmann-Sträussler-Scheinker syndrome (PRNP, p.P102L).

Gerstmann Sträussler Scheinker (GSS) is an inherited, invariably fatal prion disease. Like other human prion diseases, GSS is caused by missense mutations in the prion protein (PrP) gene (PRNP), and by the formation and overtime accumulation of the misfolded, pathogenic scrapie PrP (PrPSc). The first mutation identified in the PRNP gene, and the one blamed as the main cause of the disease, is c.C305T:p.P102L. The Sanger sequencing method was performed on the PRNP gene for the detection of c.C305T:p.P102L mutations in a cohort of 10 subjects; moreover, a study was carried out, using Next Generation Sequencing (NGS), by sequencing a group of genes related to amyotrophic lateral sclerosis (ALS), Alzheimer's disease (AD), movement disorders and dementia which show a phenotypic profile similar to that of GSS. The results obtained from the study using NGS indicate the potential role of other genetic variants which could contribute to the various GSS phenotypes. In conclusion, we highlight the large clinical variability in subjects presenting with GSS and p.P102L, as well as the hypothesis that the mutation in PrP codon 102 alone is not sufficient to trigger the cardinal clinical signs of the disease; furthermore, we do not exclude the possibility that further genetic variants play a decisive role in the aspects of the various phenotypes with which GSS manifests itself.

Elevated E200K Somatic Mutation of the Prion Protein Gene (PRNP) in the Brain Tissues of Patients with Sporadic Creutzfeldt-Jakob Disease (CJD).

Sporadic Creutzfeldt-Jakob disease (CJD) is a major human prion disease worldwide. CJD is a fatal neurodegenerative disease caused by an abnormal prion protein (PrPSc). To date, the exact etiology of sporadic CJD has not been fully elucidated. We investigated the E200K and V203I somatic mutations of the prion protein gene (PRNP) in sporadic CJD patients and matched healthy controls using pyrosequencing. In addition, we estimated the impact of somatic mutations on the human prion protein (PrP) using PolyPhen-2, PANTHER and PROVEAN. Furthermore, we evaluated the 3D structure and electrostatic potential of the human PrP according to somatic mutations using DeepView. The rates of PRNP K200 somatic mutation were significantly increased in the frontal cortex and hippocampus of sporadic CJD patients compared to the matched controls. In addition, the electrostatic potential of the human PrP was significantly changed by the K200 somatic mutation of the PRNP gene. To the best of our knowledge, this is the first report on an association of the PRNP K200 somatic mutation with sporadic CJD.

Novel Prion Protein Gene Polymorphisms in Awassi Sheep in Three Regions of the Fertile Crescent.

Scrapie is a fatal, neurodegenerative disease that affects sheep and goats, and genetic susceptibility to scrapie in sheep is associated with polymorphisms in the prion protein (PRNP) gene. The aim of this study is to identify PRNP polymorphism in Awassi sheep from Türkiye, the Palestinian Authority, and Saudi Arabia. A total of 150 healthy sheep were genotyped for PRNP, using Sanger sequencing. There were seven alleles and eleven genotypes observed based on codons 136, 154, and 171 of PRNP. The ARQ allele was predominant in all populations. The most resistant allele to scrapie, ARR, was present in all three regions. The VRQ allele, associated with the highest susceptibility to scrapie, was detected only in Türkiye at a low frequency. In this study, twenty-seven amino acid substitutions were found. Eight of them (R40Q, G65E, H88L, S98T, A118P, S138T, V192F and L250I) have not been previously reported. These data indicate that sheep breeds close to the sheep domestication center have maintained high genetic diversity in the PRNP region. Our findings on PRNP will provide valuable insights for sheep breeding programs, aiding in the selection of genotypes resistant to scrapie in Türkiye, the Palestinian Authority, and Saudi Arabia.

First report of a novel polymorphism and genetic characteristics of the leporine prion protein (PRNP) gene.

Transmissible spongiform encephalopathies (TSEs) have been reported in a broad spectrum of hosts. The genetic polymorphisms and characteristics of the prion protein (PRNP) gene have a vital impact on the development of TSEs. Notably, natural TSE infection cases have never been reported in rabbits, and genetic variations of the leporine PRNP gene have not been investigated to date. To identify leporine PRNP gene polymorphism, we performed amplicon sequencing in 203 rabbits. We report a novel single nucleotide polymorphism on the leporine PRNP gene. In addition, we performed a comparative analysis of amino acid sequences of prion protein (PrP) across several hosts using ClustalW2. Furthermore, we evaluated the effect of changes of unique leporine PrP amino acids with those conserved among various species using Swiss-Pdb Viewer. Interestingly, we found seven unique leporine amino acids, and the change of unique leporine amino acids with those conserved among other species, including S175N, Q221K, Q221R, A226Y, A230G, and A230S, was predicted to reduce hydrogen bonds in leporine PrP.

Pooled analysis of patients with inherited prion disease caused by two- to twelve-octapeptide repeat insertions in the prion protein gene (PRNP).

Inherited prion diseases caused by two- to twelve-octapeptide repeat insertions (OPRIs) in the prion protein gene (PRNP) show significant clinical heterogeneity. This study describes a family with two new cases with a 4-OPRI mutation and two asymptomatic mutation carriers. The pooled analysis summarizes all cases reported in the literature to date and describes the relation between survival, age of onset, number of OPRI and codon 129 polymorphism. MEDLINE and Google Scholar were queried from database inception up to December 31, 2022. Age of onset was compared per number of OPRI and per codon 129 polymorphism using the Kruskal-Wallis and Wilcoxon-Mann-Whitney tests, respectively. Disease duration was modeled non-parametrically by a Kaplan-Meier model and semi-parametrically by a Cox model. This study comprised 164 patients. Lower number of OPRI and presence of valine (cis-V) versus methionine (cis-M) on codon 129 were associated with an older age of onset (P < 0.001 and P = 0.025, respectively) and shorter disease duration (P < 0.001 and P = 0.003, respectively). Within patients with 5- or more OPRI codon cis-V remained significantly associated with a shorter disease duration. Codon 129 homozygosity versus heterozygosity was not significantly associated with age of onset or disease duration (P = 0.076 and P = 0.409, respectively). This study summarized the largest cohort of patients with two- to twelve-OPRI to date. Lower number of OPRI and codon 129 cis-V is associated with an older age of onset and shorter disease duration, while homozygosity or heterozygosity on codon 129 was not.

Novel histotypes of sporadic Creutzfeldt–Jakob disease linked to 129MV genotype

The MV1 and MV2 subtypes of sporadic Creutzfeldt–Jakob disease (sCJD) are linked to the heterozygous methionine (M)/valine (V) polymorphism at codon 129 of the prion protein (PrP) gene. MV2 is phenotypically heterogeneous, whereas MV1, due to its low prevalence, is one of the least well characterized subtypes. In this study, we investigated the biochemical properties of PrPSc and phenotypic expression of cases diagnosed as sCJD MV1 and MV2. We describe four MV2 histotypes: 2C, with cortical (C) coarse pathology; 2K, with kuru (K) plaque deposits; 2C-K, with co-existing C and K histotypic features; and the novel histotype 2C-PL that mimics 2C in the cerebral cortex and cerebellum, but exhibits plaque-like (PL) PrP deposits in subcortical regions (e.g., basal nuclei, thalamus and midbrain). Histotype prevalence is highest for 2C-K (55%), intermediate for 2C (31%), and lowest for 2C-PL and 2K (7%). Nearly every MV2 case expressed both PrPSc types, with T2 being the predominant type (“MV2-1”). MV1 cases typically show a rapid disease course (≤ 4 months), and feature the 1C histotype, phenotypically identical to sCJDMM1. Co-existing PrPSc types, with T1 significantly exceeding T2 (“MV1-2”), are detected in patients diagnosed as MV1 with longer disease courses. We observed four histotypes among MV1-2 cases, including two novel histotypes: 1V, reminiscent of sCJDVV1; 1C-2C, resembling sCJDMM1-2 with predominant MM1 histotypic component; and novel histotypes 1C-2PL and 1C-2K, overall mimicking 1C in the cerebral cortex, but harboring T2 and plaque-like PrP deposits in subcortical regions (1C-2PL), and T2 and kuru plaques in the cerebellum (1C-2K). Lesion profiles of 1C, 1V, and 1C-2C are similar, but differ from 1C-2PL and 1C-2K, as the latter two groups show prominent hippocampal and nigral degeneration. We believe that the novel “C-PL” histotypes are distinct entities rather than intermediate forms between “C” and “C-K” groups, and that 1C-2PL and 1C-2K histotypes may be characterized by different T1 variants of the same size.