RESUMO
Scrapie is a transmissible spongiform encephalopathy (TSE) which affects sheep and goats. TSEs are characterised by the conversion of the cellular prion protein (PrP(C)) into the pathological form PrP(Sc). The occurrence of scrapie in sheep is influenced by polymorphisms in the PrP gene; in particular, three codons (136, 154 and 171) are important in conditioning the susceptibility/resistance of sheep to the disease, with the Val/Val(136) Arg/Arg(154) Gln/Gln(171) genotype being the most susceptible and the Ala/Ala(136) Arg/Arg(154) Arg/Arg(171), the most resistant one. The latter genotype seems to confer, in sheep, resistance to the oral infection with bovine spongiform encephalopathy, as well. The selection of genetically resistant sheep populations represents the basis of the recent strategies against ovine TSE in the European Union (EU). Herein, we describe a rapid and simple method, based on the primer extension technique, for PrP genotype determination at codons 136, 154 and 171. Intra-laboratory validation of the method showed accuracy levels comparable to those of sequencing analysis. Such method could be used for both the application of the EU policies requiring PrP genotype analysis in all ovine TSE cases, and the large-scale genotyping claimed by the implementation of breeding programmes for genetic resistance to TSE in sheep.
Assuntos
Primers do DNA/normas , Testes Genéticos/métodos , Técnicas de Amplificação de Ácido Nucleico , Príons/genética , Animais , Sequência de Bases , Códon , Predisposição Genética para Doença , Genótipo , Variações Dependentes do Observador , Doenças Priônicas/genética , Reprodutibilidade dos Testes , OvinosRESUMO
Several PrP gene polymorphisms modulate sheep scrapie susceptibility. Recently, an increase of scrapie outbreaks has been reported in Italy. A vaccine containing sheep brain homogenate was used in most of the outbreaks. We investigated PrP gene polymorphisms in scrapie-affected and clinically healthy Sarda breed sheep from a flock exposed to the aforementioned vaccine, and in affected Sarda sheep from unexposed flocks. All affected animals were (Gln/Gln)171 homozygous. Moreover, we observed no variation for Ala136 and a new polymorphism (Lys to Asn) at codon 176. Our findings confirm the correlation between scrapie and (Gln/Gln)171 in breeds with no variation for Ala136.
Assuntos
Príons/genética , Scrapie/genética , Animais , Sequência de Bases , Códon , Predisposição Genética para Doença , Genótipo , Dados de Sequência Molecular , Polimorfismo Genético , Coelhos , OvinosRESUMO
Creutzfeldt-Jakob disease (CJD) belongs to a group of chronic, progressive, neurodegenerative disorders that may be hereditary, infectious, or sporadic. Hereditary CJDs are associated with mutations in the PRNP gene on chromosome 20p12-pter. We report a family in which four patients developed classical clinical signs of CJD, including severe cognitive decline, cerebellar signs, myoclonic jerks, and synchronic periodic discharges on electroencephalogram. The E211Q mutation has been identified in family members, but not in 97 sporadic CJD patients referred to the Italian registry of CJD nor in 205 healthy normal subjects, suggesting a pathogenic role for this mutation.
Assuntos
Códon/genética , Síndrome de Creutzfeldt-Jakob/genética , Proteínas PrPSc/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , Substituição de Aminoácidos , DNA/química , DNA/genética , Análise Mutacional de DNA , Saúde da Família , Feminino , Humanos , Masculino , Mutação , Linhagem , Mutação PuntualRESUMO
Creutzfeldt-Jakob disease (CJD) and related disorders occur in sporadic, acquired and inherited forms. In sporadic, iatrogenic and new variant CJD the polymorphic codon 129 of the prion protein gene (PRNP) plays an important role for the susceptibility to the disease and for the clinical and neuropathological manifestations. All the inherited forms of CJD and related disorders are linked to point or insert mutations of PRNP. The analysis of PRNP is therefore important for a correct classification of these disorders and for the identification of novel mutations. The aim of the present study is to describe a fast and easy to perform method for the direct sequencing of the PCR amplified PRNP open reading frame, by using M13 tailed primers which allow a direct and rapid method of sequencing. The goodness of this method is demonstrated in the analysis of three sporadic CJD patients with different genotypes at codon 129 and three inherited cases bearing different point mutations of PRNP: the Pro102Leu mutation linked to Gerstmann-Sträussler-Scheinker-syndrome, the Val210Ile mutation and a novel mutation at codon 211 (Gln211Glu) both associated to familial CJD.
Assuntos
Síndrome de Creutzfeldt-Jakob/genética , Análise Mutacional de DNA/métodos , Testes Genéticos/métodos , Mutação Puntual/genética , Príons/genética , Humanos , Fases de Leitura Aberta/genéticaRESUMO
Creutzfeldt-Jakob disease (CJD) and other transmissible spongiform encephalopathies (TSEs) are characterised by the accumulation of a pathological conformer of PrP, named PrPsc. Molecular weight and glycosylation of the protease-resistant core of PrPsc (PrP27-30) are heterogeneous in different forms of TSEs. We analysed PrP27-30 glycotypes in a large number of TSE-affected patients: 50 sporadic CJD (sCJD), 1 iatrogenic CJD, 1 Gerstmann-Sträussler-Scheinker syndrome (GSS) with the Pro102Leu mutation of PrP, 3 familial CJD (fCJD) with the Glu200Lys mutation and, for the first time, 7 fCJD with the Val210ll3e mutation. All patients were screened for the polymorphic codon 129 of the PrP gene. PrP27-30 deglycosylation and PrPsc immunohistochemistry were performed in selected cases. We found that two PrP27-30 glycotypes (type 1A and type 2A) are produced in sCJD. Type 1A is more frequently associated with methionine than valine in position 129. Type 1A is also formed in Val210lle fCJD. In Glu200Lys fCJD and GSS patients, we found that PrP27-30 has the same mobility of type 1 but different glycosylation ratios (type 1B). Our findings indicate that the polymorphic residue 129 of PrP has a leading role in determining the proteinase degradation site of PrPsc while mutant residues 102 or 200 influence only the glycosylation pattern.
Assuntos
Encéfalo/metabolismo , Síndrome de Creutzfeldt-Jakob/genética , Príons/química , Príons/genética , Substituição de Aminoácidos , Encéfalo/patologia , Códon/genética , Síndrome de Creutzfeldt-Jakob/etiologia , Síndrome de Creutzfeldt-Jakob/metabolismo , Humanos , Doença Iatrogênica , Mutação Puntual , Príons/isolamento & purificação , Isoformas de Proteínas/química , Isoformas de Proteínas/genética , Isoformas de Proteínas/isolamento & purificaçãoRESUMO
The authors report a new kindred with fatal familial insomnia (FFI)--an inherited prion disease. The propositus had behavioral, sleep, cognitive, and motor impairment associated with thalamic and olivary atrophy. Spongiosis was confined to the parahippocampal gyrus. Protease-resistant prion protein (PrP(res)) was present with widespread distribution. The propositus fits the histopathology of FFI with similar clinical duration and confirms the role of disease duration in determining histopathology and PrP(res) distribution in FFI.
Assuntos
Encéfalo/patologia , Proteínas PrPSc/análise , Doenças Priônicas/genética , Idade de Início , Códon , Transtornos Cognitivos , Feminino , Heterozigoto , Homozigoto , Humanos , Itália , Masculino , Pessoa de Meia-Idade , Linhagem , Mutação Puntual , Doenças Priônicas/patologia , Doenças Priônicas/fisiopatologia , Doenças Priônicas/psicologia , Transtornos do Sono-VigíliaAssuntos
Síndrome de Creutzfeldt-Jakob/epidemiologia , Síndrome de Creutzfeldt-Jakob/genética , Príons/genética , Adulto , Idoso , Análise por Conglomerados , Síndrome de Creutzfeldt-Jakob/etnologia , Humanos , Incidência , Israel/etnologia , Itália/epidemiologia , Tábuas de Vida , Pessoa de Meia-Idade , Mutação Puntual , Príons/isolamento & purificação , Probabilidade , População Rural , Eslováquia/etnologiaRESUMO
In Creutzfeldt-Jakob disease (CJD), a transmissible spongiform encephalopathy, the deposition of the pathological prion protein (PrP-res) in the brain of affected individuals is the key event that triggers the appearance of the disease. Since a polymorphism in the signal peptide of the serine-protease inhibitor alpha1 antichymotrypsin (ACT) is one of the factors that may enhance amyloid formation, we studied this polymorphism in 63 CJD patients and 103 control subjects. No difference in allele frequencies and genotype distribution was found between CJD cases and controls, nor any difference was found between the ACT genotype and the age at onset and disease duration. Interestingly, there was a significantly different (P = 0.04) ACT distribution between CJD patients and controls in apolipoprotein E (ApoE) E4, and the interaction between ACT and ApoE was almost significant (P = 0.053). Further studies on a larger number of patients will clarify whether this association can identify a possible risk factor for CJD.
Assuntos
Síndrome de Creutzfeldt-Jakob/genética , Polimorfismo Genético/genética , alfa 1-Antiquimotripsina/genética , Adulto , Apolipoproteína E4 , Apolipoproteínas E/genética , Feminino , Humanos , MasculinoRESUMO
We present a new, large, Italian family affected by Gerstmann-Sträussler-Scheinker syndrome (GSS) associated with the Pro to Leu point mutation at codon 102 of the prion protein gene (PRNP). The affected members of this family show a remarkable phenotypic variability of the disease: three of them had a clinical picture characterized by dementia and a brief illness duration (less than 1 year), while the other five members presented an ataxic, slowly evolving syndrome (a clinical duration of 3 to 4 years) with no evidence of cognitive impairment. Despite these remarkable clinical differences among affected members, we found no correlation between the clinical presentation and the codon 129 or codon 219 genotypes. These data suggest that factors as yet unidentified may influence the clinical expression of the disease.
Assuntos
Doença de Gerstmann-Straussler-Scheinker/genética , Polimorfismo Genético , Príons/genética , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Mutação , Linhagem , FenótipoAssuntos
Códon , Síndrome de Creutzfeldt-Jakob/genética , Mutação Puntual , Chile , Feminino , Humanos , Pessoa de Meia-Idade , LinhagemRESUMO
We assessed the apolipoprotein E (ApoE) genotype in 49 sporadic and ten familial Creutzfeldt-Jakob disease (CJD) patients, in seven healthy siblings with a PRNP mutation and in 84 controls. In sporadic CJD, ApoE genotypes and allelic frequencies do not significantly differ from that of controls. No influence of ApoE genotypes on age at onset was found. In familial cases, the disease appeared in mutated subjects showing the same ApoE genotype as members who have not yet developed CJD. Our results provide further evidence that ApoE is not a risk factor for CJD.
Assuntos
Apolipoproteínas E/metabolismo , Síndrome de Creutzfeldt-Jakob/metabolismo , Idoso , Idoso de 80 Anos ou mais , Alelos , Apolipoproteínas E/genética , Síndrome de Creutzfeldt-Jakob/genética , Feminino , Marcadores Genéticos , Genótipo , Humanos , Itália , Masculino , Fatores de RiscoRESUMO
Creutzfeldt-Jakob disease (CJD) is a transmissible neurodegenerative disorder characterized by the accumulation of the amyloid protein PrP in the CNS. Two coding polymorphisms of the PrP gene (PRNP) are a methionine (Met) to valine (Val) change at codon 129, and a deletion in the octapeptide coding region. In the United Kingdom, homozygosity at codon 129 appears to be associated with a predisposition to develop CJD. However, in Japan, where allelic frequencies and genotype distribution are significantly different, such an association has not been demonstrated. To determine whether such deletion(s) or codon 129 polymorphisms of PRNP predispose to the development of CJD in Italian patients, 31 sporadic CJD patients with no known PRNP mutations, and 186 unrelated control subjects were studied. Genotypic frequencies at codon 129 in these Italian CJD patients revealed a significant excess of methionine alleles, and a different genotype distribution in comparison with the normal Italian population. Deletions of a 24-bp segment located in the PrP octapeptide coding region were found in two control subjects, but in none of the sporadic CJD patients. These data suggest that Met homozygosity at codon 129 may contribute, with other environmental or endogenous factors, to CJD development.