Submitted by Edisangela Bastos (edisangela@ufpa.br) on 2013-12-02T21:46:40Z No. of bitstreams: 2 license_rdf: 22974 bytes, checksum: 99c771d9f0b9c46790009b9874d49253 (MD5) Tese_AlteracoesGeneticasEpigeneticas.pdf: 1341053 bytes, checksum: 3c3dc3d55f7d58401af456f5fcaabb7c (MD5) / Approved for entry into archive by Ana Rosa Silva(arosa@ufpa.br) on 2013-12-06T17:20:43Z (GMT) No. of bitstreams: 2 license_rdf: 22974 bytes, checksum: 99c771d9f0b9c46790009b9874d49253 (MD5) Tese_AlteracoesGeneticasEpigeneticas.pdf: 1341053 bytes, checksum: 3c3dc3d55f7d58401af456f5fcaabb7c (MD5) / Made available in DSpace on 2013-12-06T17:20:43Z (GMT). No. of bitstreams: 2 license_rdf: 22974 bytes, checksum: 99c771d9f0b9c46790009b9874d49253 (MD5) Tese_AlteracoesGeneticasEpigeneticas.pdf: 1341053 bytes, checksum: 3c3dc3d55f7d58401af456f5fcaabb7c (MD5) Previous issue date: 2013 / CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / FAPESPA - Fundação Amazônia de Amparo a Estudos e Pesquisas / Os meningiomas são os tumores intracranianos mais frequentes, originando-se das meninges que revestem o cérebro e cordão espinhal. Apesar de terem sido um dos primeiros neoplasmas sólidos estudados citogeneticamente, ainda são escassos os estudos genéticos e epigenéticos nesses tumores. O presente trabalho teve como objetivo investigar alterações genéticas e epigenéticas que pudessem contribuir na iniciação e progressão tumoral em meningiomas na população paraense. Essa tese está subdivida em três capítulos. No Capítulo I foi investigada a associação entre o polimorfismo MTHFR C677T e meningioma em 23 pacientes da população paraense, utilizando 96 indivíduos sem histórico de lesões pré-neoplásicas como grupo controle. Essa associação não foi encontrada, apesar de sugerir um aumento não estatisticamente significante no risco de desenvolver meningioma em portadores do genótipo TT quando comparados ao genótipo CC. No Capítulo II foi avaliado o padrão de metilação em duas famílias do microRNA124 em meningiomas na população paraense. Hipermetilação na região promotora de miRN124a2 e miRNA124a3 parece ser um evento frequente, uma vez que foi encontrada em 73,9% e 69,56% das amostras analisadas, respectivamente. No Capítulo III, foi analisado o padrão de metilação dos genes APC, BRCA1, CDH1, CDH13, CDKN2A, DAPK1, ESR1, FHIT, GSTP1, MGMT, MLH1, NEUROG1, PDLIM4, PTEN, RARB, RASSF1, RUNX3, SOCS1, TIMP3, TP73, VHL e WIF1 em um meningioma de grau I e um de grau II através de uma placa comercial desenvolvida através da tecnologia MethylScreen. O padrão de metilação do gene CDKN2B também foi analisado na amostra coletada em 25 pacientes com meningioma através da conversão por bissulfito, PCR e sequenciamento direto. O gene RASSF1A apresentou-se metilado em 16,73% e 63,66% dos sítios CpGs analisados na amostra de meningioma de grau I e grau II, respectivamente. O gene RUNX3 se apresentou metilado apenas na amostra de grau II em 52,88% dos sítios CpG analisados. Nossos resultados apontam a importância das alterações epigenéticas na tumorigênese e progressão tumoral em meningiomas. / Meningiomas are the most common intracranial tumors that originate from the meninges surrounding the brain and spinal cord. Despite meningiomas were among the first solid neoplasms to be studied cytogenetically, little is known about their genetic and epigenetic profile. This study aimed to investigate genetic and epigenetic alterations that could contribute to tumor initiation and progression in meningiomas in the population of Pará, Brazil. This thesis is subdivided into three chapters. In Chapter I we investigated the association between the MTHFR C677T and meningioma in 23 patients in the population of Pará. A total of 96 healthy individuals with no previous pre-neoplastic lesions were selected for the control group. This association was not found. Although not statistically significant, our observation suggests that the TT genotype increases the risk of developing meningioma when compared to CC genotype. In Chapter II we evaluated the methylation pattern in two members of microRNA124 family in meningiomas in the population of Pará. Hypermethylation of the promoter region of miRN124a2 and miRNA124a3 appears to be a frequent event, as was found in 73.9% and 69.56% of the samples, respectively. In Chapter III, we analyzed the methylation pattern of the APC, BRCA1, CDH1, CDH13, CDKN2A, DAPK1, ESR1, FHIT, GSTP1, MGMT, MLH1, NEUROG1, PDLIM4, PTEN, Rb, RASSF1, RUNX3, SOCS1, TIMP3, TP73, VHL and WIF1 genes in a grade I and in a grade II meningiomas through an assay developed by MethylScreen. Pattern of methylation of CDKN2B was also analyzed in 25 patients with meningioma through bisulfite conversion, PCR and direct sequencing. RASSF1A was methylated in 16.73% and 63.66% of the CpG sites analyzed in the grade I and grade II meningioma, respectively. RUNX3 is methylated only in grade II meningioma in 52.88% of the CpG sites analyzed. Our results point to the importance of epigenetic changes in tumorigenesis and tumor progression in meningiomas.

Introdução: A homocistinúria clássica é um erro inato do metabolismo causado pela atividade deficiente da cistationina β-sintase (CβS). É caracterizada pela elevação sérica de homocisteína e metionina e redução dos níveis de cisteína. As manifestações clínicas clássicas envolvem os sistemas ocular, vascular, nervoso central e ósseo. Entretanto, observações recentes sugerem que alterações na composição corporal, especialmente a redução de tecido adiposo, também pode ser uma manifestação frequente e clinicamente relevante nesta doença. Além disso, a gravidade do fenótipo clínico parece ser influenciada por outros genes além do CβS. O objetivo deste estudo foi investigar alterações na composição corporal e detectar mutações comuns nos genes CβS, MTHFR e F5 em pacientes com homocistinúria clássica; relacionando dados clínicos, bioquímicos e genéticos. Métodos: Realizada avaliação da composição corporal em 8 pacientes através de duas técnicas: antropometria (aferição das dobras cutâneas triciptal, biciptal, subescapular e suprailíaca) e bioimpedância elétrica (BIA). A partir dos resultados obtidos, calculou-se o percentual de gordura pelas fórmulas de Siri (antropometria) e Kushner (BIA). O índice de massa corporal (IMC) também foi calculado. Os níveis de metionina, homocisteína e cisteína foram mensurados por HPLC. A avaliação genotípica foi realizada em 11 pacientes através de PCR-RFLP. Pesquisadas as mutações p.I278T, p.T191M, p.G307S e c.844ins68 no gene CβS; c.677TC>T e c.1298A>C no gene MTHFR; e p.R506Q no gene F5 (Fator V de Leiden). Resultados: Cinco pacientes apresentaram baixo percentual de gordura por pelo menos um dos métodos; o restante apresentou percentual médio. De acordo com o IMC, apenas dois pacientes foram classificados em baixo peso. O percentual de gordura total não se relacionou com os achados bioquímicos ou ósseos, mas medida isolada da dobra cutânea triciptal correlacionou-se positivamente com os níveis de cisteína (p=0,03) Além disso, os níveis de homocisteína e metionina correlacionaram-se negativamente com o IMC, enquanto que a cisteína teve associação positiva (p<0.05). Houve tendência do escore T de fêmur associar-se negativamente com homocisteína e positivamente com cisteína (p=0,09). Entre as mutações do gene CβS, a p.1278T foi a única encontrada (n= 3/9 famílias); entretanto, em 2/3 famílias estava em cis com a c.844ins68. Assim, em apenas um caso tinha caráter patogênico. Não foi possível estabelecer associação entre mutações em MTHFR e F5 e a gravidade do fenótipo. Conclusões: Os resultados sugerem que deficiência de CβS gera alterações significativas na composição corporal – observou-se redução do percentual de gordura independentemente do IMC. Este pode ser um mecanismo patogênico importante envolvido na etiologia da 2 osteoporose na homocistinúria clássica, mas estudos adicionais são necessários para demonstrar esta relação. Os achados sugerem que as mutações patogênicas no gene CBS sejam raras ou privadas nesta amostra, e não corroboram a ação dos genes MTHFR e F5 como modificadores da doença. / Introduction: Classical homocystinuria is an inborn error of metabolism caused by the deficient activity of cystathionine β-synthase (CβS). It is characterized by plasma increase in homocysteine and methionine and a decrease in cysteine levels. Its classical clinical manifestations involve the following systems: ocular, vascular, central nervous, and skeletal. However, recent observations have suggested that changes in the body composition, especially a reduction of the adipose tissue, may also be a frequent manifestation of the disease and clinically relevant to it. Moreover, the severity of its clinical phenotype may be influenced by other genes besides CβS. The objective of the present study was to investigate alterations in the body composition and to detect common mutations in CβS, MTHFR and F5 genes in patients with classical homocystinuria and to correlate them to the clinical, biochemical, and genetic data. Methods: Body composition was assessed in 8 patients using the techniques of anthropometry (measurement of the following skinfolds: triciptal, biciptal, subscapular, and suprailiac) and electrical bioimpedance (BIA). Based on the results obtained, the percentage of body fat was calculated using the formulas of Siri (anthropometry) and Kushner (BIA). The body mass index (BMI) was also calculated. The levels of methionine, homocysteine, and cysteine were measured by HPLC. The genotypic evaluation was done in 11 patients by PCR-RFLP. The following mutations were investigated: p.I278T, p.T191M, p.G307S, and c.844ins68 in the CβS gene; c.677TC>T and c.1298A>C in the MTHFR gene; and p.R506Q in the F5 gene (Factor V Leiden). Results: Five patients presented low percentage of body fat by at least one of the methods; the other patients presented a medium percentage. According to the BMI, only 2 patients were classified as being underweight. The percentage of total body fat was not related to either bone or biochemical findings, but the isolate measurement of the triciptal skinfold was positively correlated to the levels of cysteine (p=0.03). Also, the levels of homocysteine and methionine were negatively correlated to the BMI, while cysteine had a positive association (p<0.05). The T score of the femur tended to associate negatively with homocysteine and positively with cysteine (p=0.09). The genetic evaluation revealed only one pathogenic mutation in CβS (p.I278T). An association between mutations in MTHFR and F5 and phenotype severity could not be established. Conclusions: The present results suggest that the deficiency of CβS causes significant alterations in the body composition; a reduction of the percentage of body fat was observed independently from the BMI. This may be an important pathogenic mechanism involved in the etiology of osteoporosis in classical homocystinuria. The present findings suggest that in this sample the 4 pathogenic mutations in the CBS gene are rare or private and do not corroborate with the action of the MTHFR and F5 genes as disease modifiers. Further studies are needed.

Multiple Sclerosis (MS) is a neurodegenerative disease of the central nervous system (CNS). As part of this disorder the myelin sheath undergoes degeneration, leading to alterations in the conductivity of axons, and impaired function. The onset of the disease occurs in young adults and clinical pathology is characterised by varying severity. These include i) Relapsing Remitting MS (RR-MS), ii) Secondary Progressive MS (SP-MS) and iii) Primary Progressive MS (PP-MS). MS is more prevalent in women and accounts for more than two thirds of all MS sufferers. MS is considered to be a multifactorial disorder with both genetic and environmental components. The prevalence of MS is dependent on geographical localisation, with lower sunlight exposure linked to higher prevalence. Also, studies show an increased risk in close relatives, or in identical twins, indicating a significant genetic component to the disorder. There are a number of genes that may plausibly be involved in MS pathophysiology. These include myelin-related genes, such as the myelin basic protein (MBP), immune-related genes, such FC receptor and osteopontin, and heat shock proteins such as xb crystallin. These candidate genes have been implicated in a variety of ways but usually through immunological and/or genetic studies. One of the most consistent findings in recent years has been the association of disease with alterations in the specific major histocompatibility complex (MHC) localised to chromosome 6p21.3, and includes MHC I, II, III. Genome wide screens have permitted the identification of loci in the genome, which are associated with MS susceptibility. The number of genes involved in MS is unknown and several case-control association studies have been undertaken to reveal the involvement of potential candidate genes. In general terms, current research is aimed at determining allelic variation of candidate genes. Such genes have been implicated in MS because they reside within susceptible regions of the chromosome associated with MS or they have a plausible potential pathophysiological role in MS. Candidate loci investigated in this study, for association with MS susceptibility, include members of the nitric oxide synthase family of metabolic proteins (inducible NOS, iNOS/NOS2A and neuronal NOS, nNOS), methylenetetrahydrofolate reductase (MTHFR), catechol-O-methyl transferase (COMT), and vitamin D receptor (VDR). The MS population used in all studies consisted of over 100 MS cases and gender, age and ethnicity matched controls. In our study of inducible and neuronal NOS genes, PCR based assays were developed to amplify a region of both promoters that contained known microsatellite variation. Supporting phyisological data suggests that the neuroinflammatory aspects of MS are associated with aberrant NO production, which may be due to aberrant regulation of NOS activity. Specific amplified products were identified by fluorescent capillary electrophoresis and allele frequencies were statistically compared using chi-squared analysis. In the nNOS and iNOS study, no association was identified with allele frequency variation and MS susceptibility (nNOS: ?2=5.63, P=0.962; iNOS: ?2=3.4; P=0.082). Similarly, no differences in allele frequencies were observed for gender or clinical course for both markers (Pvalue greater than 0.05). In short, results from this study indicate that the NOS promoter variations studied do not play a significant role in determining susceptibility to MS in the tested population. The COMT and MTHFR genes are localised at 22q12-13 and 1p36.3 respectively, regions of the genome that have been found to be positively associated with MS susceptibility. In our research, we set out to examine the G158A change in the 4th exon of the COMT gene. This functional mutation leads to an amino acid change (valine to methionine) that is directly associated with changes in the activity of COMT. The MTHFR enzyme plays a role in folate metabolism, and can be implicated in the turnover of homocysteine. Previous investigations have shown that high levels of homocysteine are encountered in MS patients, where it is also linked to demyelination in the CNS. In our study the aim was to examine the C677T variation (alanine to valine amino acid change) in the exon 4 coding region of the MTHFR gene and the G158A variation in the COMT gene. Restriction fragment length polymorphism (RFLP) analysis and gel electrophoresis was used to identify specific alleles for both COMT and MTHFR. However, as with the NOS study, no specific association was identified between MS susceptibility and variation for either of the tested COMT or MTHFR (Pvalue greater than 0.05) variants. In a final genomic investigation of the MS population, three variations in the VDR gene were analysed for association with MS susceptibility and pathology. Using RFLP analysis, three VDR variants were investigated with genotypes detected using the Taq I, Apa I and Fok I restriction enzymes. In contrast to previous genotypic analyses, this study did show a positive association, specifically between the functional variation in exon 9 of the VDR gene and MS (Taq I, 2= 7.22, P= 0.0072). Interestingly, the Apa I variant of VDR was also found to be associated with MS ( 2=4.2, P=0.04). The Taq I and Apa I variants were also found to be in very strong and significant linkage disequilibrium (D'=0.96, Pvalue less than 0.0001) and their associations were more prominent with the progressive forms of MS (SP-MS and PP-MS). In addition to genotypic analysis of a clinical population, additional research was undertaken to identify novel targets for MS susceptibility studies. Global gene expression analysis was undertaken using comparative subtractive fluorescent microarray technology to examine differences in gene activity (expression) in age and sex matched MS plaque tissue and anatomically matched normal white matter (NWM). MS plaques were obtained post mortem from MS sufferers with no drug history in the last two months before death and matched anatomically to healthy white matter from donors with no previous neurological disorders. Target arrays consisted of 5000 cDNAs and analysis was conducted using the Affymetrix 428 scanner. In this way, 139 genes were shown to be differentially regulated in MS plaque tissue compared to NWM. Of these, 69 genes showed a common pattern of expression in the chronic active and acute plaque tissues investigated (Pvalue less than 0.0001, a=0.73); while 70 transcripts were uniquely differentially expressed ( 1.5-fold) in either acute or chronic active lesions. To validate the gene expression profile results, quantitative real time reverse transcriptase (RT) PCR (Q-PCR) analysis was performed. 12 genes were selected because they were shown to be differentially expressed by array analysis in this study, or because of their involvement in MS pathology. These included transferrin (TF), superoxide dismutase 1 (SOD1), glutathione peroxidase 1 (GPX1), glutathione S-transferase pi (GSTP1), crystallin, alpha-B (CRYAB), phosphomannomutase 1 (PMM1), tubulin beta-5 (TBB5), inositol 1,4,5-trisphosphate 3-kinase B (ITPKB), calpain 1 (CAPNS1), osteopontin (SPP1 or OPN), as well as the signal transducer and activator of transcription 1 (STAT1) and protein inhibitor of activated STAT1 (PIAS1). Both absolute (copy number) and comparative differences in the relative levels of expression in MS lesions and NWM were determined for each gene. The results from this study revealed a significant correlation of real time PCR results with the microarray data, while a significant correlation was also found between comparative and absolute determinations of fold. As with the results of array analysis, a significant difference in gene expression patterning was identified between chronic active and acute plaque pathologies. For example, a up to 50-fold increase in SPP1 and ITPKB levels in acute plaques contrasted with the 5-fold or less increase in chronic active plaques (P less than 0.0.1, unpaired t-Test). Of particular note, gamma-amino butyric acid receptor ?2 (GABG2), integrin ?5 (ITGB5), complement component 4B (C4B), parathyroid hormone receptor 1 (PTHR1) were found up-regulated in MS and glial derived neurotropic factor ?2 (GDNFA2), insulin receptor (INSR), thyroid hormone receptor ZAKI4 (ZAKI4) were found down-regulated in MS. Data also revealed a decreased expression of the immune related genes STAT1 and PIAS1 in acute plaques. In conclusion, this research used both genomic analysis and technologies in gene expression to investigate both known and novel markers of MS pathology and susceptibility. The study developed tools that may be used for further investigation of clinical pathology in MS and have provided interesting initial expression data to further investigate the genes that play a role in MS development and progression.

A suscetibilidade ao câncer se apresenta com diferentes freqüências em diferentes populações. Dentre muitas das estudadas está a população judaica Ashkenazi, que vêm sendo alvo de muitos trabalhos por apresentarem doenças genéticas em proporção maior do que seria esperado para outra população qualquer. Tal incidência provavelmente advém do fato de terem sofrido dois grandes bottlenecks ao longo de sua história, gerando um efeito fundador que seria responsável pela alta incidência de doenças genéticas. O gene TP53 tem papel importante em um grande número de processos celulares e o polimorfismo Arg72Pro (R72P) deste gene leva a diferenças funcionais em atividades biológicas e bioquímicas, o que parece estar intimamente ligado ao câncer de mama. Da mesma forma, acredita-se que a variação genética de genes para metilenotetrahidrofolato redutase (MTHFR), enzima essencial no metabolismo um-carbono, pode alterar os níveis de metilação do DNA e influenciar a carcinogênese. Buscou-se então verificar qual a prevalência do polimorfismo R72P e dos polimorfismos de MTHFR (A1298C e C677T) em mulheres judias Ashkenazi de Porto Alegre. Para isto, foi utilizado material biológico proveniente de 255 mulheres Ashkenazi residentes na cidade de Porto Alegre e 255 amostras de um grupo controle de doadores saudáveis do hospital de clínicas de Porto Alegre, para amplificação das regiões de interesse através da técnica de PCR seguida por digestão com enzimas de restrição específicas. O polimorfismo R72P mostrou uma freqüência genotípica de ~61% Arg/Arg, ~37% Arg/Pro e ~2% Pro/Pro nas mulheres judaicas Ashkenazi; em comparação com a amostra controle que mostrou uma freqüência genotípica de ~43% Arg/Arg, ~44% Arg/Pro e 13% Pro/Pro. Com relação aos polimorfismos de MTHFR, obteve-se os seguintes resultados para judias e controles, respectivamente: 677CC (31 e 42%), 677CT (47 e 48%), 677TT (22 e 10%), 1298AA (49,4 e 60%), 1298AC (43,1 e 35%) e 1298CC (7,5 e 5%). Os resultados estatísticos mostraram-se significativos para as freqüências alélicas e genotípicas (P<0,001 para R72P; P=0,000 para C677T e P=0,041 para A1298C). Ampliar e diversificar as amostras se faz necessário para avaliar consistentemente como a influência das diferenças étnicas e raciais podem afetar os resultados dos estudos, além de aspectos como alimentação, fumo, hábito de beber, casamentos consangüíneos, entre outros, devem ser considerados nas análises de dados, buscando uma melhor resposta em relação às hipóteses levantadas e assim eliminando da análise possíveis fatores de confusão. / Cancer susceptibility is presented with different frequencies in different populations. Among the many populations studied, the Ashkenazi Jewish have been the subject of several scientific publications due to the greater proportion of genetic diseases observed than would be expected for any other population. This effect probably stands from the fact that they had suffered two major bottlenecks throughout its history, resulting in a founder effect that would be responsible for high incidence of genetic diseases. TP53 gene has an important role in many cellular processes and the Arg72Pro (R72P) polymorphism of this gene leads to functional differences in biochemical and biological activities, which seems to be closely linked to breast cancer. It is also believed that the genetic variation of genes for methylenetetrahydrofolate reductase (MTHFR), an essential enzyme of the one-carbon metabolism, can alter levels of DNA methylation and influence carcinogenesis. We sought to determine how prevalent are R72P and MTHFR (C677T; A1298C) polymorphisms in a group of Ashkenazi Jewish women from Porto Alegre. For this, we used biological material from 255 Ashkenazi women living in Porto Alegre and 255 samples from a control group of healthy donors of Hospital de Clinicas de Porto Alegre, for amplification of interest regions by PCR followed by digestion with specific restriction enzymes. The R72P polymorphism showed a genotype frequency of ~ 61% Arg / Arg, ~ 37% Arg / Pro and ~ 2% Pro / Pro in the Ashkenazi Jewish, compared to the control sample which showed a genotype frequency of ~ 43% Arg /Arg, Arg ~ 44% / 13% Pro and Pro / Pro. Regarding the MTHFR polymorphisms we obtained the following results for Jewish and controls, respectively: 677CC (31 and 42%), 677CT (47 and 48%), 677TT (22 and 10%), 1298AA (49.4 and 60%), 1298AC (43.1 and 35%) and 1298CC (7.5 and 5%). The statistical results were significant for allele and genotype frequencies (P <0.001 for R72P, P = 0.000 for C677T and A1298C to P = 0.041). Increasing the sample number and studying several worldwide populations is needed to consistently evaluate the influence of ethnic and racial differences which may affect the results obtained. In addition to that, aspects such as diet, smoking, drinking, consanguineous marriages, among others, should be considered in the data analysis in order to seek for a better response to the hypotheses raised, thus eliminating possible confounding factors.

A suscetibilidade ao câncer se apresenta com diferentes freqüências em diferentes populações. Dentre muitas das estudadas está a população judaica Ashkenazi, que vêm sendo alvo de muitos trabalhos por apresentarem doenças genéticas em proporção maior do que seria esperado para outra população qualquer. Tal incidência provavelmente advém do fato de terem sofrido dois grandes bottlenecks ao longo de sua história, gerando um efeito fundador que seria responsável pela alta incidência de doenças genéticas. O gene TP53 tem papel importante em um grande número de processos celulares e o polimorfismo Arg72Pro (R72P) deste gene leva a diferenças funcionais em atividades biológicas e bioquímicas, o que parece estar intimamente ligado ao câncer de mama. Da mesma forma, acredita-se que a variação genética de genes para metilenotetrahidrofolato redutase (MTHFR), enzima essencial no metabolismo um-carbono, pode alterar os níveis de metilação do DNA e influenciar a carcinogênese. Buscou-se então verificar qual a prevalência do polimorfismo R72P e dos polimorfismos de MTHFR (A1298C e C677T) em mulheres judias Ashkenazi de Porto Alegre. Para isto, foi utilizado material biológico proveniente de 255 mulheres Ashkenazi residentes na cidade de Porto Alegre e 255 amostras de um grupo controle de doadores saudáveis do hospital de clínicas de Porto Alegre, para amplificação das regiões de interesse através da técnica de PCR seguida por digestão com enzimas de restrição específicas. O polimorfismo R72P mostrou uma freqüência genotípica de ~61% Arg/Arg, ~37% Arg/Pro e ~2% Pro/Pro nas mulheres judaicas Ashkenazi; em comparação com a amostra controle que mostrou uma freqüência genotípica de ~43% Arg/Arg, ~44% Arg/Pro e 13% Pro/Pro. Com relação aos polimorfismos de MTHFR, obteve-se os seguintes resultados para judias e controles, respectivamente: 677CC (31 e 42%), 677CT (47 e 48%), 677TT (22 e 10%), 1298AA (49,4 e 60%), 1298AC (43,1 e 35%) e 1298CC (7,5 e 5%). Os resultados estatísticos mostraram-se significativos para as freqüências alélicas e genotípicas (P<0,001 para R72P; P=0,000 para C677T e P=0,041 para A1298C). Ampliar e diversificar as amostras se faz necessário para avaliar consistentemente como a influência das diferenças étnicas e raciais podem afetar os resultados dos estudos, além de aspectos como alimentação, fumo, hábito de beber, casamentos consangüíneos, entre outros, devem ser considerados nas análises de dados, buscando uma melhor resposta em relação às hipóteses levantadas e assim eliminando da análise possíveis fatores de confusão. / Cancer susceptibility is presented with different frequencies in different populations. Among the many populations studied, the Ashkenazi Jewish have been the subject of several scientific publications due to the greater proportion of genetic diseases observed than would be expected for any other population. This effect probably stands from the fact that they had suffered two major bottlenecks throughout its history, resulting in a founder effect that would be responsible for high incidence of genetic diseases. TP53 gene has an important role in many cellular processes and the Arg72Pro (R72P) polymorphism of this gene leads to functional differences in biochemical and biological activities, which seems to be closely linked to breast cancer. It is also believed that the genetic variation of genes for methylenetetrahydrofolate reductase (MTHFR), an essential enzyme of the one-carbon metabolism, can alter levels of DNA methylation and influence carcinogenesis. We sought to determine how prevalent are R72P and MTHFR (C677T; A1298C) polymorphisms in a group of Ashkenazi Jewish women from Porto Alegre. For this, we used biological material from 255 Ashkenazi women living in Porto Alegre and 255 samples from a control group of healthy donors of Hospital de Clinicas de Porto Alegre, for amplification of interest regions by PCR followed by digestion with specific restriction enzymes. The R72P polymorphism showed a genotype frequency of ~ 61% Arg / Arg, ~ 37% Arg / Pro and ~ 2% Pro / Pro in the Ashkenazi Jewish, compared to the control sample which showed a genotype frequency of ~ 43% Arg /Arg, Arg ~ 44% / 13% Pro and Pro / Pro. Regarding the MTHFR polymorphisms we obtained the following results for Jewish and controls, respectively: 677CC (31 and 42%), 677CT (47 and 48%), 677TT (22 and 10%), 1298AA (49.4 and 60%), 1298AC (43.1 and 35%) and 1298CC (7.5 and 5%). The statistical results were significant for allele and genotype frequencies (P <0.001 for R72P, P = 0.000 for C677T and A1298C to P = 0.041). Increasing the sample number and studying several worldwide populations is needed to consistently evaluate the influence of ethnic and racial differences which may affect the results obtained. In addition to that, aspects such as diet, smoking, drinking, consanguineous marriages, among others, should be considered in the data analysis in order to seek for a better response to the hypotheses raised, thus eliminating possible confounding factors.

Introdução: A homocistinúria clássica é um erro inato do metabolismo causado pela atividade deficiente da cistationina β-sintase (CβS). É caracterizada pela elevação sérica de homocisteína e metionina e redução dos níveis de cisteína. As manifestações clínicas clássicas envolvem os sistemas ocular, vascular, nervoso central e ósseo. Entretanto, observações recentes sugerem que alterações na composição corporal, especialmente a redução de tecido adiposo, também pode ser uma manifestação frequente e clinicamente relevante nesta doença. Além disso, a gravidade do fenótipo clínico parece ser influenciada por outros genes além do CβS. O objetivo deste estudo foi investigar alterações na composição corporal e detectar mutações comuns nos genes CβS, MTHFR e F5 em pacientes com homocistinúria clássica; relacionando dados clínicos, bioquímicos e genéticos. Métodos: Realizada avaliação da composição corporal em 8 pacientes através de duas técnicas: antropometria (aferição das dobras cutâneas triciptal, biciptal, subescapular e suprailíaca) e bioimpedância elétrica (BIA). A partir dos resultados obtidos, calculou-se o percentual de gordura pelas fórmulas de Siri (antropometria) e Kushner (BIA). O índice de massa corporal (IMC) também foi calculado. Os níveis de metionina, homocisteína e cisteína foram mensurados por HPLC. A avaliação genotípica foi realizada em 11 pacientes através de PCR-RFLP. Pesquisadas as mutações p.I278T, p.T191M, p.G307S e c.844ins68 no gene CβS; c.677TC>T e c.1298A>C no gene MTHFR; e p.R506Q no gene F5 (Fator V de Leiden). Resultados: Cinco pacientes apresentaram baixo percentual de gordura por pelo menos um dos métodos; o restante apresentou percentual médio. De acordo com o IMC, apenas dois pacientes foram classificados em baixo peso. O percentual de gordura total não se relacionou com os achados bioquímicos ou ósseos, mas medida isolada da dobra cutânea triciptal correlacionou-se positivamente com os níveis de cisteína (p=0,03) Além disso, os níveis de homocisteína e metionina correlacionaram-se negativamente com o IMC, enquanto que a cisteína teve associação positiva (p<0.05). Houve tendência do escore T de fêmur associar-se negativamente com homocisteína e positivamente com cisteína (p=0,09). Entre as mutações do gene CβS, a p.1278T foi a única encontrada (n= 3/9 famílias); entretanto, em 2/3 famílias estava em cis com a c.844ins68. Assim, em apenas um caso tinha caráter patogênico. Não foi possível estabelecer associação entre mutações em MTHFR e F5 e a gravidade do fenótipo. Conclusões: Os resultados sugerem que deficiência de CβS gera alterações significativas na composição corporal – observou-se redução do percentual de gordura independentemente do IMC. Este pode ser um mecanismo patogênico importante envolvido na etiologia da 2 osteoporose na homocistinúria clássica, mas estudos adicionais são necessários para demonstrar esta relação. Os achados sugerem que as mutações patogênicas no gene CBS sejam raras ou privadas nesta amostra, e não corroboram a ação dos genes MTHFR e F5 como modificadores da doença. / Introduction: Classical homocystinuria is an inborn error of metabolism caused by the deficient activity of cystathionine β-synthase (CβS). It is characterized by plasma increase in homocysteine and methionine and a decrease in cysteine levels. Its classical clinical manifestations involve the following systems: ocular, vascular, central nervous, and skeletal. However, recent observations have suggested that changes in the body composition, especially a reduction of the adipose tissue, may also be a frequent manifestation of the disease and clinically relevant to it. Moreover, the severity of its clinical phenotype may be influenced by other genes besides CβS. The objective of the present study was to investigate alterations in the body composition and to detect common mutations in CβS, MTHFR and F5 genes in patients with classical homocystinuria and to correlate them to the clinical, biochemical, and genetic data. Methods: Body composition was assessed in 8 patients using the techniques of anthropometry (measurement of the following skinfolds: triciptal, biciptal, subscapular, and suprailiac) and electrical bioimpedance (BIA). Based on the results obtained, the percentage of body fat was calculated using the formulas of Siri (anthropometry) and Kushner (BIA). The body mass index (BMI) was also calculated. The levels of methionine, homocysteine, and cysteine were measured by HPLC. The genotypic evaluation was done in 11 patients by PCR-RFLP. The following mutations were investigated: p.I278T, p.T191M, p.G307S, and c.844ins68 in the CβS gene; c.677TC>T and c.1298A>C in the MTHFR gene; and p.R506Q in the F5 gene (Factor V Leiden). Results: Five patients presented low percentage of body fat by at least one of the methods; the other patients presented a medium percentage. According to the BMI, only 2 patients were classified as being underweight. The percentage of total body fat was not related to either bone or biochemical findings, but the isolate measurement of the triciptal skinfold was positively correlated to the levels of cysteine (p=0.03). Also, the levels of homocysteine and methionine were negatively correlated to the BMI, while cysteine had a positive association (p<0.05). The T score of the femur tended to associate negatively with homocysteine and positively with cysteine (p=0.09). The genetic evaluation revealed only one pathogenic mutation in CβS (p.I278T). An association between mutations in MTHFR and F5 and phenotype severity could not be established. Conclusions: The present results suggest that the deficiency of CβS causes significant alterations in the body composition; a reduction of the percentage of body fat was observed independently from the BMI. This may be an important pathogenic mechanism involved in the etiology of osteoporosis in classical homocystinuria. The present findings suggest that in this sample the 4 pathogenic mutations in the CBS gene are rare or private and do not corroborate with the action of the MTHFR and F5 genes as disease modifiers. Further studies are needed.

Introdução: A homocistinúria clássica é um erro inato do metabolismo causado pela atividade deficiente da cistationina β-sintase (CβS). É caracterizada pela elevação sérica de homocisteína e metionina e redução dos níveis de cisteína. As manifestações clínicas clássicas envolvem os sistemas ocular, vascular, nervoso central e ósseo. Entretanto, observações recentes sugerem que alterações na composição corporal, especialmente a redução de tecido adiposo, também pode ser uma manifestação frequente e clinicamente relevante nesta doença. Além disso, a gravidade do fenótipo clínico parece ser influenciada por outros genes além do CβS. O objetivo deste estudo foi investigar alterações na composição corporal e detectar mutações comuns nos genes CβS, MTHFR e F5 em pacientes com homocistinúria clássica; relacionando dados clínicos, bioquímicos e genéticos. Métodos: Realizada avaliação da composição corporal em 8 pacientes através de duas técnicas: antropometria (aferição das dobras cutâneas triciptal, biciptal, subescapular e suprailíaca) e bioimpedância elétrica (BIA). A partir dos resultados obtidos, calculou-se o percentual de gordura pelas fórmulas de Siri (antropometria) e Kushner (BIA). O índice de massa corporal (IMC) também foi calculado. Os níveis de metionina, homocisteína e cisteína foram mensurados por HPLC. A avaliação genotípica foi realizada em 11 pacientes através de PCR-RFLP. Pesquisadas as mutações p.I278T, p.T191M, p.G307S e c.844ins68 no gene CβS; c.677TC>T e c.1298A>C no gene MTHFR; e p.R506Q no gene F5 (Fator V de Leiden). Resultados: Cinco pacientes apresentaram baixo percentual de gordura por pelo menos um dos métodos; o restante apresentou percentual médio. De acordo com o IMC, apenas dois pacientes foram classificados em baixo peso. O percentual de gordura total não se relacionou com os achados bioquímicos ou ósseos, mas medida isolada da dobra cutânea triciptal correlacionou-se positivamente com os níveis de cisteína (p=0,03) Além disso, os níveis de homocisteína e metionina correlacionaram-se negativamente com o IMC, enquanto que a cisteína teve associação positiva (p<0.05). Houve tendência do escore T de fêmur associar-se negativamente com homocisteína e positivamente com cisteína (p=0,09). Entre as mutações do gene CβS, a p.1278T foi a única encontrada (n= 3/9 famílias); entretanto, em 2/3 famílias estava em cis com a c.844ins68. Assim, em apenas um caso tinha caráter patogênico. Não foi possível estabelecer associação entre mutações em MTHFR e F5 e a gravidade do fenótipo. Conclusões: Os resultados sugerem que deficiência de CβS gera alterações significativas na composição corporal – observou-se redução do percentual de gordura independentemente do IMC. Este pode ser um mecanismo patogênico importante envolvido na etiologia da 2 osteoporose na homocistinúria clássica, mas estudos adicionais são necessários para demonstrar esta relação. Os achados sugerem que as mutações patogênicas no gene CBS sejam raras ou privadas nesta amostra, e não corroboram a ação dos genes MTHFR e F5 como modificadores da doença. / Introduction: Classical homocystinuria is an inborn error of metabolism caused by the deficient activity of cystathionine β-synthase (CβS). It is characterized by plasma increase in homocysteine and methionine and a decrease in cysteine levels. Its classical clinical manifestations involve the following systems: ocular, vascular, central nervous, and skeletal. However, recent observations have suggested that changes in the body composition, especially a reduction of the adipose tissue, may also be a frequent manifestation of the disease and clinically relevant to it. Moreover, the severity of its clinical phenotype may be influenced by other genes besides CβS. The objective of the present study was to investigate alterations in the body composition and to detect common mutations in CβS, MTHFR and F5 genes in patients with classical homocystinuria and to correlate them to the clinical, biochemical, and genetic data. Methods: Body composition was assessed in 8 patients using the techniques of anthropometry (measurement of the following skinfolds: triciptal, biciptal, subscapular, and suprailiac) and electrical bioimpedance (BIA). Based on the results obtained, the percentage of body fat was calculated using the formulas of Siri (anthropometry) and Kushner (BIA). The body mass index (BMI) was also calculated. The levels of methionine, homocysteine, and cysteine were measured by HPLC. The genotypic evaluation was done in 11 patients by PCR-RFLP. The following mutations were investigated: p.I278T, p.T191M, p.G307S, and c.844ins68 in the CβS gene; c.677TC>T and c.1298A>C in the MTHFR gene; and p.R506Q in the F5 gene (Factor V Leiden). Results: Five patients presented low percentage of body fat by at least one of the methods; the other patients presented a medium percentage. According to the BMI, only 2 patients were classified as being underweight. The percentage of total body fat was not related to either bone or biochemical findings, but the isolate measurement of the triciptal skinfold was positively correlated to the levels of cysteine (p=0.03). Also, the levels of homocysteine and methionine were negatively correlated to the BMI, while cysteine had a positive association (p<0.05). The T score of the femur tended to associate negatively with homocysteine and positively with cysteine (p=0.09). The genetic evaluation revealed only one pathogenic mutation in CβS (p.I278T). An association between mutations in MTHFR and F5 and phenotype severity could not be established. Conclusions: The present results suggest that the deficiency of CβS causes significant alterations in the body composition; a reduction of the percentage of body fat was observed independently from the BMI. This may be an important pathogenic mechanism involved in the etiology of osteoporosis in classical homocystinuria. The present findings suggest that in this sample the 4 pathogenic mutations in the CBS gene are rare or private and do not corroborate with the action of the MTHFR and F5 genes as disease modifiers. Further studies are needed.

A suscetibilidade ao câncer se apresenta com diferentes freqüências em diferentes populações. Dentre muitas das estudadas está a população judaica Ashkenazi, que vêm sendo alvo de muitos trabalhos por apresentarem doenças genéticas em proporção maior do que seria esperado para outra população qualquer. Tal incidência provavelmente advém do fato de terem sofrido dois grandes bottlenecks ao longo de sua história, gerando um efeito fundador que seria responsável pela alta incidência de doenças genéticas. O gene TP53 tem papel importante em um grande número de processos celulares e o polimorfismo Arg72Pro (R72P) deste gene leva a diferenças funcionais em atividades biológicas e bioquímicas, o que parece estar intimamente ligado ao câncer de mama. Da mesma forma, acredita-se que a variação genética de genes para metilenotetrahidrofolato redutase (MTHFR), enzima essencial no metabolismo um-carbono, pode alterar os níveis de metilação do DNA e influenciar a carcinogênese. Buscou-se então verificar qual a prevalência do polimorfismo R72P e dos polimorfismos de MTHFR (A1298C e C677T) em mulheres judias Ashkenazi de Porto Alegre. Para isto, foi utilizado material biológico proveniente de 255 mulheres Ashkenazi residentes na cidade de Porto Alegre e 255 amostras de um grupo controle de doadores saudáveis do hospital de clínicas de Porto Alegre, para amplificação das regiões de interesse através da técnica de PCR seguida por digestão com enzimas de restrição específicas. O polimorfismo R72P mostrou uma freqüência genotípica de ~61% Arg/Arg, ~37% Arg/Pro e ~2% Pro/Pro nas mulheres judaicas Ashkenazi; em comparação com a amostra controle que mostrou uma freqüência genotípica de ~43% Arg/Arg, ~44% Arg/Pro e 13% Pro/Pro. Com relação aos polimorfismos de MTHFR, obteve-se os seguintes resultados para judias e controles, respectivamente: 677CC (31 e 42%), 677CT (47 e 48%), 677TT (22 e 10%), 1298AA (49,4 e 60%), 1298AC (43,1 e 35%) e 1298CC (7,5 e 5%). Os resultados estatísticos mostraram-se significativos para as freqüências alélicas e genotípicas (P<0,001 para R72P; P=0,000 para C677T e P=0,041 para A1298C). Ampliar e diversificar as amostras se faz necessário para avaliar consistentemente como a influência das diferenças étnicas e raciais podem afetar os resultados dos estudos, além de aspectos como alimentação, fumo, hábito de beber, casamentos consangüíneos, entre outros, devem ser considerados nas análises de dados, buscando uma melhor resposta em relação às hipóteses levantadas e assim eliminando da análise possíveis fatores de confusão. / Cancer susceptibility is presented with different frequencies in different populations. Among the many populations studied, the Ashkenazi Jewish have been the subject of several scientific publications due to the greater proportion of genetic diseases observed than would be expected for any other population. This effect probably stands from the fact that they had suffered two major bottlenecks throughout its history, resulting in a founder effect that would be responsible for high incidence of genetic diseases. TP53 gene has an important role in many cellular processes and the Arg72Pro (R72P) polymorphism of this gene leads to functional differences in biochemical and biological activities, which seems to be closely linked to breast cancer. It is also believed that the genetic variation of genes for methylenetetrahydrofolate reductase (MTHFR), an essential enzyme of the one-carbon metabolism, can alter levels of DNA methylation and influence carcinogenesis. We sought to determine how prevalent are R72P and MTHFR (C677T; A1298C) polymorphisms in a group of Ashkenazi Jewish women from Porto Alegre. For this, we used biological material from 255 Ashkenazi women living in Porto Alegre and 255 samples from a control group of healthy donors of Hospital de Clinicas de Porto Alegre, for amplification of interest regions by PCR followed by digestion with specific restriction enzymes. The R72P polymorphism showed a genotype frequency of ~ 61% Arg / Arg, ~ 37% Arg / Pro and ~ 2% Pro / Pro in the Ashkenazi Jewish, compared to the control sample which showed a genotype frequency of ~ 43% Arg /Arg, Arg ~ 44% / 13% Pro and Pro / Pro. Regarding the MTHFR polymorphisms we obtained the following results for Jewish and controls, respectively: 677CC (31 and 42%), 677CT (47 and 48%), 677TT (22 and 10%), 1298AA (49.4 and 60%), 1298AC (43.1 and 35%) and 1298CC (7.5 and 5%). The statistical results were significant for allele and genotype frequencies (P <0.001 for R72P, P = 0.000 for C677T and A1298C to P = 0.041). Increasing the sample number and studying several worldwide populations is needed to consistently evaluate the influence of ethnic and racial differences which may affect the results obtained. In addition to that, aspects such as diet, smoking, drinking, consanguineous marriages, among others, should be considered in the data analysis in order to seek for a better response to the hypotheses raised, thus eliminating possible confounding factors.

M. Tech (Department of Biotechnology, Faculty of Applied and Computer Sciences) Vaal University of Technology. / Background: Cardiovascular diseases are one of the most common causes of death worldwide. This is not only a problem in developed countries, it is of major concern for public health in developing countries as well. Increased homocysteine is an independent risk factor for cardiovascular diseases. Nutritional deficiencies of folate, vitamin B6 and vitamin B12 are associated with hyperhomocysteinemia. MTHFR A1298C, a single nucleotide polymorphism, is similarly linked with higher concentrations of homocysteine. The aim of this study was to determine the prevalence of MTHFR A1298C in a black elderly population, along with folate, vitamin B6 and vitamin B12 and to evaluate the effect on homocysteine levels. Methodology: The research design was an observational cross-sectional study and was ethically approved. A total of 84 elderly who attend a day-care centre (also met inclusion criteria) were purposively selected. DNA was extracted and frozen on the day of blood collection. The MTHFR A1298C genotype was determined with real time PCR. Homocysteine, folate, vitamin B6 and vitamin B12 serum levels were detected with commercial assay kits. Results: Homocysteine was found to be elevated with a median of 17.78 µmol/L (interquartile range 13.98-21.03 µmol/L). Serum folate, vitamin B6 and vitamin B12 medians were in the normal range. Although, 5.95% and 22.62% of the population were deficient and possibly deficient for vitamin B12, respectively. MTHFR A1298C frequency was as follow: 89.29% (AA), 9.52% (AC) and 1.19% (CC), with no significant correlation (p>0.05) with homocysteine. Vitamin B12 correlated significantly with homocysteine levels. Conclusion: Vitamin B12 deficiency had an effect on homocysteine levels. Overall, nutritional deficiencies are not responsible for the hyperhomocysteinemia in this population. In conclusion from this study showed MTHFR A1298C frequency in black South Africans does not contribute to homocysteine as a risk factor for cardiovascular disease. Keywords: Cardiovascular disease, elderly, folate, homocysteine, MTHFR A1298C, vitamin B6, vitamin B12.

Association of type and severity of nonsyndromic OROFACIAL CLEFTS with combined genotypes of RFC1 80 GA, MTHFR 677 CT, IRF6 rs642961 and rs2235371 gene polymorphisms in an Indian population Abstract By Chantal Hakim University of the Pacific. Arthur Dugoni School of Dentistry 2020 Introduction. Genetic etiology of nonsyndromic orofacial clefts comprises many genes acting together. However, little is known about their interactions. The purpose of our study was to analyze associations of phenotypic subtypes of nonsyndromic orofacial clefts with combinations of four genotypes involving candidate gene polymorphisms. Materials and Methods. We analyzed a large dataset of cases and controls collected in one location (Karaikal in India) and genotyped for four gene polymorphisms: RFC1 G80A, MTHFR C677T, IRF6 GA rs642961 and IRF6 CT rs2235371 (IRB approval Nr. 17-118 for existing data). The samples were tested for Hardy-Weinberg genetic equilibrium. Combinations of genotypes in cleft subsamples were compared with controls using Odds Ratio and Confidence Interval (95% significance level) calculations. Results. The Hardy-Weinberg equilibrium test showed that all samples were in genetic equilibrium. Some combinations of RFC1 G80A, MTHFR C677T, IRF6 GA rs642961 and IRF6 CT rs2235371 yielded increased or decreased Odds Ratio (OR>1 or OR<1).This means that subtypes of orofacial clefts were differentially determined by genotype combinations of four gene polymorphisms. Conclusions. Our results suggest that combinations of gene polymorphisms may modulate genetic risk in subtypes of nonsyndromic orofacial clefts. Such studies seem to be important for development of a general procedure and how a prevention plan for a specific location needs to be prepared, which data needs to be collected and which analyses need to be performed.