Genetic Prion Disease: Insight from the Features and Experience of China National Surveillance for Creutzfeldt-Jakob Disease / 神经科学通报·英文版

Human genetic prion diseases (gPrDs) are directly associated with mutations and insertions in the PRNP (Prion Protein) gene. We collected and analyzed the data of 218 Chinese gPrD patients identified between Jan 2006 and June 2020. Nineteen different subtypes were identified and gPrDs accounted for 10.9% of all diagnosed PrDs within the same period. Some subtypes of gPrDs showed a degree of geographic association. The age at onset of Chinese gPrDs peaked in the 50-59 year group. Gerstmann-Sträussler-Scheinker syndrome (GSS) and fatal familial insomnia (FFI) cases usually displayed clinical symptoms earlier than genetic Creutzfeldt-Jakob disease (gCJD) patients with point mutations. A family history was more frequently recalled in P105L GSS and D178N FFI patients than T188K and E200K patients. None of the E196A gCJD patients reported a family history. The gCJD cases with point mutations always developed clinical manifestations typical of sporadic CJD (sCJD). EEG examination was not sensitive for gPrDs. sCJD-associated abnormalities on MRI were found in high proportions of GSS and gCJD patients. CSF 14-3-3 positivity was frequently detected in gCJD patients. Increased CSF tau was found in more than half of FFI and T188K gCJD cases, and an even higher proportion of E196A and E200K gCJD patients. 63.6% of P105L GSS cases showed a positive reaction in cerebrospinal fluid RT-QuIC. GSS and FFI cases had longer durations than most subtypes of gCJD. This is one of the largest studies of gPrDs in East Asians, and the illness profile of Chinese gPrDs is clearly distinct. Extremely high proportions of T188K and E196A occur among Chinese gPrDs; these mutations are rarely reported in Caucasians and Japanese.

High phenotypic variability in Gerstmann-Sträussler-Scheinker disease / Elevada variabilidade fenotípica na doença de Gerstmann-Sträussler-Scheinker

ABSTRACT Gerstmann-Sträussler-Scheinker is a genetic prion disease and the most common mutation is p.Pro102Leu. We report clinical, molecular and neuropathological data of seven individuals, belonging to two unrelated Brazilian kindreds, carrying the p.Pro102Leu. Marked differences among patients were observed regarding age at onset, disease duration and clinical presentation. In the first kindred, two patients had rapidly progressive dementia and three exhibited predominantly ataxic phenotypes with variable ages of onset and disease duration. In this family, age at disease onset in the mother and daughter differed by 39 years. In the second kindred, different phenotypes were also reported and earlier ages of onset were associated with 129 heterozygosis. No differences were associated with apoE genotype. In these kindreds, the codon 129 polymorphism could not explain the clinical variability and 129 heterozygosis was associated with earlier disease onset. Neuropathological examination in two patients confirmed the presence of typical plaques and PrPsc immunopositivity.

RESUMO A doença de Gerstmann-Sträussler-Scheinker é uma doença priônica genética, cuja mutação mais frequente é p.Pro102Leu. Descrevem-se dados clínicos, moleculares e neuropatológicos de sete indivíduos em duas famílias não relacionadas com p.Pro102Leu. Diferenças notáveis entre os pacientes em relação à idade de início, duração da doença e apresentação clínica foram encontradas. Na primeira família, dois pacientes apresentaram demência rapidamente progressiva e três apresentaram fenótipo de ataxia com idade variáveis de início e duração da doença. Nesta família, a idade de início entre mãe e filha diferiu em 39 anos. Na segunda família, fenótipos diferentes foram observados e idades precoces de início dos sintomas foram associadas à heterozigose no códon 129. Não houve diferença em relação ao genótipo do gene da apoE. O genótipo do códon 129 não foi responsável pela variabilidade clínica; heterozigose no códon 129 esteve associada ao início precoce da doença. O exame neuropatológico em dois pacientes confirmou presença de placas típicas e imunohistoquímica para PrPsc.

Polymorphisms in the Prion Protein Gene of cattle breeds from Brazil / Polimorfismos no gene da proteína priônica em bovinos no Brasil

One of the alterations that occur in the PRNP gene in bovines is the insertion/deletion (indel) of base sequences in specific regions, such as indels of 12-base pairs (bp) in intron 1 and of 23- bp in the promoter region. The deletion allele of 23 bp is associated with susceptibility to bovine spongiform encephalopathy (BSE) as well as the presence of the deletion allele of 12 bp. In the present study, the variability of nucleotides in the promoter region and intron 1 of the PRNP gene was genotyped for the Angus, Canchim, Nellore and Simmental bovine breeds to identify the genotype profiles of resistance and/or susceptibility to BSE in each animal. Genomic DNA was extracted for amplification of the target regions of the PRNP gene using polymerase chain reaction (PCR) and specific primers. The PCR products were submitted to electrophoresis in agarose gel 3% and sequencing for genotyping. With the exception of the Angus breed, most breeds exhibited a higher frequency of deletion alleles for 12 bp and 23 bp in comparison to their respective insertion alleles for both regions. These results represent an important contribution to understanding the formation process of the Brazilian herd in relation to bovine PRNP gene polymorphisms.(AU)

Uma das mudanças que ocorrem no gene PRNP em bovinos é a inserção e/ou deleção (indels) de sequências de bases, em determinadas regiões como, por exemplo, as indels de 12 pares de bases (pb) no íntron 1 e 23pb na região promotora. O alelo de deleção de 23pb está relacionado com a suscetibilidade à Encefalopatia Espongiforme Bovina (EEB), assim como a presença do alelo de deleção de 12pb. Neste estudo foi genotipada a variabilidade de nucleotídeos da região promotora e íntron 1 do gene PRNP em bovinos das raças Angus, Canchim, Nelore e Simental, para identificar os perfis genotípicos de resistência e/ou suscetibilidade à EEB de cada animal. Foi realizada a extração de DNA genômico para amplificação das regiões alvo do gene PRNP, por meio da reação em cadeia de polimerase (PCR) utilizando-se primers específicos. Os produtos da PCR foram submetidos à eletroforese em gel de agarose a 3%, e sequenciamento para a realização da genotipagem. Com exceção da raça Angus, a maioria das raças apresentaram maiores frequências do alelo de deleção tanto para 12pb como 23pb, em comparação com seus respectivos alelos de inserção, para as duas regiões. Esses resultados abrem caminhos para o conhecimento de como o rebanho brasileiro está sendo formado com relação aos polimorfismos do gene PRNP bovino.(AU)

Conhecimento e prática dos enfermeiros sobre hanseníase: ações de controle e eliminação / Conocimiento y práctica de enfermeros acerca de hanseniasis: acciones de control y eliminación / Knowledge and practice of the nurse about leprosy: actions of control and elimination

RESUMO Objetivo: avaliar o conhecimento e a prática de enfermeiros da atenção primária de saúde quanto às ações de controle e eliminação da hanseníase. Método: estudo avaliativo, com abordagem qualitativa, utilizando o Discurso do Sujeito Coletivo, cujos dados foram obtidos por meio de entrevista semiestruturada, realizada com 16 enfermeiros. Resultados: os dados coletados revelaram que os profissionais de saúde possuem conhecimento suficiente sobre a Política Nacional de Controle e Eliminação da Hanseníase (PNCEH) e que as principais ações preconizadas foram executadas, porém, a notificação de casos suspeitos ou confirmados e a reinserção social do doente não foram citadas. Conclusão: manter os doentes em tratamento, sobrecarga de trabalho, falta de interdisciplinaridade e tratamento realizado em outros locais fora da comunidade foram dificuldades relatadas pelos profissionais. Os enfermeiros conhecem as ações direcionadas à assistência ao hanseniano, entretanto, o estudo aponta para a necessidade de uma prática mais alinhada ao que preconiza a PNECH. .

RESUMEN Objetivo: evaluar el conocimiento y la práctica de los enfermeros que trabajan en la atención primaria de salud como las acciones de control y eliminación de la hanseniasis. Método: es un estudio evaluativo con enfoque cualitativo, utilizando el Discurso del Sujeto Colectivo, cuyos datos fueron recolectados a través de entrevistas semi-estructuradas con 16 enfermeros. Resultados: los datos obtenidos revelaron que los profesionales de la salud tienen el conocimiento suficiente sobre la Política Nacional de Control y Erradicación de la Hanseniasis (PNCEH) y que las principales acciones recomendadas se han implementado, pero la notificación de los casos sospechosos o confirmados y reinserción social del paciente no fue mencionado. Conclusión: mantener a los pacientes en tratamiento, exceso de trabajo, falta de interdisciplinariedad y tratamiento realizado en otros lugares fuera de la comunidad fueron problemas reportados por el personal de salud. Los enfermeros conocen las acciones destinadas a ayudar a los pacientes con hanseniasis, sin embargo, el estudio apunta la necesidad de una practica más direccionado a lo que defiende la PNECH. .

ABSTRACT Objective: to assess the knowledge and practice of primary health care nurses about control and elimination actions of leprosy. Method: evaluation study with qualitative approach, using the Discourse of the Collective Subject, data were collected through semi-structured interviews conducted with 16 nurses. Results: the data collected revealed that health professionals have suffi cient knowledge about the National Policy on Control and Elimination of Leprosy (NPCEL) and that the main actions preconized were applied, however, notifi cation of suspected or confi rmed cases and social reintegration of the patient were not mentioned. Conclusion: keeping patients in treatment, overload of work, lack of interdisciplinarity and treatment performed at other locations outside of the community were diffi culties reported by professionals. Nurses know the actions addressed at assistance of leprosy patients, however, the study points to the need for a practice which is more aligned to what advocates NPCEL. .

Genetic Studies in Human Prion Diseases

Human prion diseases are fatal neurodegenerative disorders that are characterized by spongiform changes, astrogliosis, and the accumulation of an abnormal prion protein (PrP(Sc)). Approximately 10%-15% of human prion diseases are familial variants that are caused by pathogenic mutations in the prion protein gene (PRNP). Point mutations or the insertions of one or more copies of a 24 bp repeat are associated with familial human prion diseases including familial Creutzfeldt-Jakob disease (CJD), Gerstmann-Straussler-Scheinker syndrome, and fatal familial insomnia. These mutations vary significantly in frequency between countries. Here, we compare the frequency of PRNP mutations between European countries and East Asians. Associations between single nucleotide polymorphisms (SNPs) of several candidate genes including PRNP and CJD have been reported. The SNP of PRNP at codon 129 has been shown to be associated with sporadic, iatrogenic, and variant CJD. The SNPs of several genes other than PRNP have been showed contradictory results. Case-control studies and genome-wide association studies have also been performed to identify candidate genes correlated with variant and/or sporadic CJD. This review provides a general overview of the genetic mutations and polymorphisms that have been analyzed in association with human prion diseases to date.

Codon 129 polymorphism of prion protein gene in is not a risk factor for Alzheimer's disease / Polimorfismo do codon 129 do gene da proteina prionica nao e fator de risco para doenca de Alzheimer

Interaction of prion protein and amyloid-b oligomers has been demonstrated recently. Homozygosity at prion protein gene (PRNP) codon 129 is associated with higher risk for Creutzfeldt-Jakob disease. This polymorphism has been addressed as a possible risk factor in Alzheimer disease (AD). Objective To describe the association between codon 129 polymorphisms and AD. Methods We investigated the association of codon 129 polymorphism of PRNP in 99 AD patients and 111 controls, and the association between this polymorphism and cognitive performance. Other polymorphisms of PRNP and additive effect of apolipoprotein E gene (ApoE) were evaluated. Results Codon 129 genotype distribution in AD 45.5% methionine (MM), 42.2% methionine valine (MV), 12.1% valine (VV); and 39.6% MM, 50.5% MV, 9.9% VV among controls (p>0.05). There were no differences of cognitive performance concerning codon 129. Stratification according to ApoE genotype did not reveal difference between groups. Conclusion Codon 129 polymorphism is not a risk factor for AD in Brazilian patients.

Polimorfismo do códon 129 do gene da proteína priônica não é fator de risco para doença de Alzheimer A interação entre proteína priônica e oligômeros b-amiloide foi demonstrada recentemente. Homozigose no códon 129 do gene da proteína priônica (PRNP) é fator de risco para doença de Creutzfeldt-Jakob. Este polimorfismo foi estudado como possível fator de risco para doença de Alzheimer (DA). Objetivo Estudar uma possível associação entre o polimorfismo do códon 129 e DA. Métodos Foram investigados 99 pacientes com DA e 111 controles em relação ao polimorfismo do códon 129 e sua associação com desempenho cognitivo. Foram pesquisados outros polimorfismos do PRNP e efeito aditivo do gene da apolipoproteína E (ApoE). Resultados Distribuição no códon 129: 45,5% metionina (MM), 42,2% metionina valina (MV), 12,1% valina (VV) nos pacientes com DA; e 39,6% MM, 50,5% MV, 9,9% VV, nos controles (p >0.05). Não houve diferença no desempenho cognitivo em relação ao códon 129. Estratificação pelo genótipo do ApoE não mostrou diferença entre grupos. Conclusão Polimorfismo do códon 129 não é fator de risco para DA em pacientes brasileiros.

Sequence variations of the bovine prion protein gene (PRNP) in native Korean Hanwoo cattle

Bovine spongiform encephalopathy (BSE) is one of the fatal neurodegenerative diseases known as transmissible spongiform encephalopathies (TSEs) caused by infectious prion proteins. Genetic variations correlated with susceptibility or resistance to TSE in humans and sheep have not been reported for bovine strains including those from Holstein, Jersey, and Japanese Black cattle. Here, we investigated bovine prion protein gene (PRNP) variations in Hanwoo cattle [Bos (B.) taurus coreanae], a native breed in Korea. We identified mutations and polymorphisms in the coding region of PRNP, determined their frequency, and evaluated their significance. We identified four synonymous polymorphisms and two non-synonymous mutations in PRNP, but found no novel polymorphisms. The sequence and number of octapeptide repeats were completely conserved, and the haplotype frequency of the coding region was similar to that of other B. taurus strains. When we examined the 23-bp and 12-bp insertion/deletion (indel) polymorphisms in the non-coding region of PRNP, Hanwoo cattle had a lower deletion allele and 23-bp del/12-bp del haplotype frequency than healthy and BSE-affected animals of other strains. Thus, Hanwoo are seemingly less susceptible to BSE than other strains due to the 23-bp and 12-bp indel polymorphisms.

Familial Creutzfeldt-Jakob Disease with V180I Mutation

Creutzfeldt-Jakob disease (CJD) is an uncommon neurodegenerative disorder with an incidence of 1 per 1000,000 per year typically characterized by rapidly progressive dementia, ataxia, myoclonus and behavioral changes. Genetic prion diseases, which develop due to a mutations in the prion protein gene (PRNP), account for an estimated 10 to 15% of all CJD cases. We report a 75-yr-old woman with familial CJD carrying a V180I mutation which features late onset, slow progression, no periodic sharp wave complexes on electroencephalography, and extensive cortical ribboning with spared the cerebellum and the medial occipital lobes posterior to the parieto-occipital sulcus on MRI. To our knowledge, this is the first documented case of a point mutation at codon 180 in South Korea.

Genetic variability of the prion protein gene (PRNP) in wild ruminants from Italy and Scotland

The genetics of the prion protein gene (PRNP) play a crucial role in determining the relative susceptibility to transmissible spongiform encephalopathies (TSEs) in several mammalian species. To determine the PRNP gene variability in European red deer (Cervus elaphus), roe deer (Capreolus capreolus) and chamois (Rupicapra rupicapra), the PRNP open reading frame from 715 samples was analysed to reveal a total of ten single nucleotide polymorphisms (SNPs). In red deer, SNPs were found in codons 15, 21, 59, 78, 79, 98, 136, 168 and 226. These polymorphisms give rise to 12 haplotypes, and one of which is identical to the PRNP of American wapiti (Rocky Mountain elk, Cervus elaphus nelsoni). One silent mutation at codon 119 was detected in chamois and no SNPs were found in roe deer. This analysis confirmed that European wild ruminants have a PRNP genetic background that is compatible with TSE susceptibility, including chronic wasting disease.

Identification of single-nucleotide polymorphisms of the prion protein gene in sika deer (Cervus nippon laiouanus)

Polymorphisms of the prion protein gene (PRNP) havebeen detected in several cervid species. In order toconfirm the genetic variations, this study examined theDNA sequences of the PRNP obtained from 33 captivesika deer (Cervus nippon laiouanus) in Korea. A total ofthree single-nucleotide polymorphisms (SNPs) at codons100, 136 and 226 in the PRNP of the sika deer wereidentified. The polymorphic site located at codon 100 hasnot been reported. The SNPs detected at codons 100 and226 induced amino acid substitutions. The SNP at codon136 was a silent mutation that does not induce any aminoacid change. The genotype and allele frequencies weredetermined for each of the SNPs.

Forma familiar de la enfermedad de Creutzfeldt-Jakob: marcadores genéticos en 4 familias chilenas / Genetic markers in four Chilean families with familial Creutzfeldt-Jakob disease

Background: Creutzfeldt-Jakob disease (CJD) is a form of transmissible spongiform encephalopathy, in which a prion protein (PrP Sc) accumulates in the brain of affected individuals. Chile has a prevalence of CJD that is more than twice than in the rest of the world and has the highest rate of familial forms. These later forms are associated with the heterozygocity of codon 200 of PrP protein gene. Aim: To search susceptibility genetic markers of CJD in members of families affected by CJD. Material and methods: A blood sample was obtained from 50 individuals pertaining to four families affected by CJD. DNA from peripheral mononuclear cells was amplified by polymerase chain reaction and sequenced for the gene that codifies PrP protein. Results: In family A, 21 of 23 members were homozygotes for codon 129 (Met/Met) and eight were simultaneously heterozygotes for codon 200 (Glu/Lys). In family B, six of nine members were homozygotes for codon 129, five were heterozygotes for codon 200 and four had both mutations. In family C, the four analyzed subjects were homozygotes for codon 129 and two were simultaneously heterozygotes for codon 200. In family D, nine of 14 members were homozygotes for codon 129 and two were simultaneously homozygotes for codon 200. No family had polymorphisms for codon 219. Conclusions: Thirty two percent of analyzed subjects were homozygotes for codon 129 and heterozygotes for codon 200, condition that defines the genetic susceptibility to acquire CJD. The dominant tendency of these genotypes could explain the higher incidence of CJF in Chile.

No association of prion protein gene polymorphisms with Alzheimer's disease in Korean population

The polymorphism at codon 129 (M129V) of the human prion protein gene (PRNP) is a known risk factor for Creutzfeldt-Jakob disease (CJD) in Caucasians. There are few reports of this polymorphism's effect on memory and on the risk of Alzheimer's disease (AD). The M129V genotype distributions among Asians are very different from Caucasians. Another polymorphism, codon 219 (E219K) is not found in Caucasians. We investigated two polymorphisms of PRNP, M129V (rs1799990) and E219K (rs1800014) in 297 Korean AD patients and 217 healthy subjects. The analysis of the genotype and allele distributions showed no significant difference between the AD patients and the controls in both polymorphisms (P=0.19 genotype, P=0.51 allele for M129V; P=0.64 genotype, P=0.50 allele for E219K). Also, the PRNP polymorphisms were not significantly associated with AD when the populations were stratified for the presence or absence of apolipoprotein E-e4 (ApoE-epsilon4) allele. These results suggest that the PRNP genetic variants are not associated with the risk for AD in Korean population.

Encefalopatía de Creutzfeldt - Jakob con mutación E200K: a propósito de un caso reportado como 'esporádico' / Creutzfeldt-Jakob encephalopathy with mutation E2000K: report of a \"Sporadic\" case

La encefalopatía de Creutzfeldt Jakob (ECJ), es la de mayor incidencia dentro del grupo de las encefalopatías espongiformes transmisibles o enfermedades por priones, las que tienen como característica única entre todas las patologías, la de poder presentarse como esporádica, infecciosa/ iatrogénica, o hereditaria.Se han descrito mas de 20 mutaciones del gen (PRNP) que codifica la proteína prion, capaces de generar la ECJ en su forma hereditaria o familiar (fECJ). Se comunica un caso que fue referido como CJ 'esporádico' probable según criterios de la OMS y resultó después del estudio molecular, CJ familiar E200K.

Proteína prion celular em doenças humanas não-priônicas: aspectos moleculares e celulares / Cellular prion protein in non prionic human diseases: molecular and cellular aspects

Encefalopatias espongiformes são doenças priônicas que afetam humanos e animais. O agente infeccioso, PrPsc é uma isoforma anormal de uma proteína celular, PrPc, que é expressa em todas as células e altamente conservada entre as espécies. As funções até então conhecidas da proteína normal PrPc, a relacionam com neuroplasticidade, neuritogenese, neuroproteção, além de participação na proteção ao estresse oxidativo. Este trabalho abordou algumas destas características avaliando a proteína PrPc em algumas doenças humanas não priônicas. Baseado em dados obtidos em camundongos que não expressam a proteína PrPc, onde várias alterações foram descritas como hiperexcitabilidade neuronal, além de alta sensibilidade a agentes convulsivantes, investigamos o envolvimento de PrPccom síndromes epilépticas humanas. Analisamos a seqüência do gene que codifica PrPc (Prnp) em indivíduos com epilepsia refratária ao tratamento farmacológico portadores de epilepsia de lobo temporal mesial associada à esclerose hipocampal (ELTM-EH, n=100) e epilepsias focais associadas a anormalidades do desenvolvimento cortical (ADC, n=68), que foram comparadas com um grupo controle (n=180)... Nossos resultados mostraram que não há variantes alélicas prevalentes nestes pacientes. Investigamos então, a expressão da proteína PrPc por método imunoistoquímico, nos gliomas mais prevalentes, os astrocitomas... Acrescentamos ao estudo a pesquisa da expressão de STI-1 (stress inducible protein-I) ligante de PrPc associado a neuroproteção, n-NOS (neuronal nitric oxide sintase) e I-NOS (inducible nitric oxide sintase), enzimas de síntese de óxido nítrico, que estão relacionadas a função de proteção a estresse oxidativo descrito para a proteína PrPc (AU)

Prions are the infectious agents that cause neurodegenerative diseases, called Transmissible Spongiform Encephalopathies, both in humans and animais. In fact, they are a counterpart o f the cellular prion protein (PrPc) which is expressed in most cell types and is conserved among species, suggesting its important role in the cellular physiology. PrPc has a pivotal role in protection against oxidative stress, neuritogenesis, neuroplasticity and neuroprotection. Therefore, the present work aimed to evaluate the PrPc participation human maladies other than prion diseases based on these functions of the normal protein. Mice with the PrPc gene (Prnp) ablated show neuronal hiperexcitability and enhanced sensitivity to seizures, indicating that PrPc might be related to epilepsy. Here~ we evaluated the genetic contribution of Prnp to the human medically untreatable Mesial Temporal Lobe Epilepsy related to Hippocampal Sclerosis MTLE-HS) and in Malformations of Cortical Development (MCD). DNA obtained fron1 peripheral blood cells was used to evaluate Prnp coding sequence from 100 patients with surgically treated MTLE-HS and 68 patients with different forms of (MCD). These data were further compared with a control healthy group with similar demographic characteristics (n=180). A Prnp variant allele at codon 171, Asn171Ser, which was absent in the contro l group, was highly prevalent in patients with MTLEHS (23%) and MCD (13%). This rare polymorphism was also associated with the worst surgical outcome in MTLE-HS. Seizure history has been associated with some brain tumors and our next approach was evaluate Prnp variant alleles in patients with gliomas (n = 49). Some ofthe Prnp polymorphisms were present, however their frequency was similar to that found in the normal population. PrPc has been associated to protection against oxidative stress and its binding to the Stress Inducible protein 1 (STil) mediates neuroprotection. The we investigated PrPc, STI-1 and nvo oxidative enzymes: i-NOS and n-NOS, expression in astrocyton1.as (n = 109), using inm1unohistochemistry. Our data shows that astrocitomas grade II and III have lower PrPc, STI-1 and n-NOS leveis when compared with normal brain tissues. However, glioblastomas showed higher PrPc and n-NOS expression than astrocitomas II and III. These results indicate that PrPc expression could be related to tumor malignancy. We further performed the same expression analysis using a tissue microarray constructed with 25 different human tumors: neuroblastoma, retinoblastoma, pancreatic and prostatic adenocarcinoma, invasive ductal breast cancer, carcinoid tumor, malignant melanoma and head and neck squamous cell carcinoma. The correspondent normal tissue was also included in this construction. PrPc and i-NOS presented a high expression in invasive ductal breast cancer in contrast with normal breast tissue where no stain was observed in ductal cells. In retinoblasto1nas, STI-1 expression was lower in non differentiated tumors than in differentiated ones. On the other hand, PrPc tends to decrease in invasive and metastatic tumors particularly in neuroblastomas. Finally, our data points that PrPc polymorphisms contribute to a higher predisposition to epilepsies and is also a predictive factor for surgery outcome. Furthermore, we observed an alteration on PrPc and its ligand STil expression pattern in human tumors sue h as astrocytomas, retino blastomas and ductal invasive breast carcinoma, suggesting that these proteins can be implicated in the tumor process. Further investigations will be necessary to delineate the cellular and molecular mechanisms involved with these observations (AU)