Análise genética da produção in vitro de embriões em bovinos Guzerá

O objetivo dessa pesquisa foi avaliar aspectos genéticos que relacionados à produção in vitro de embriões na raça Guzerá. O primeiro estudo focou na estimação de (co) variâncias genéticas e fenotípicas em características relacionadas a produção de embriões e na detecção de possível associação com a idade ao primeiro parto (AFC). Foi detectada baixa e média herdabilidade para características relacionadas à produção de oócitos e embriões. Houve fraca associação genética entre características ligadas a reprodução artificial e a idade ao primeiro parto. O segundo estudo avaliou tendências genéticas e de endogamia em uma população Guzerá no Brasil. Doadoras e embriões produzidos in vitro foram considerados como duas subpopulações de forma a realizar comparações acerca das diferenças de variação anual genética e do coeficiente de endogamia. A tendência anual do coeficiente de endogamia (F) foi superior para a população geral, sendo detectado efeito quadrático. No entanto, a média de F para a sub- população de embriões foi maior do que na população geral e das doadoras. Foi observado ganho genético anual superior para a idade ao primeiro parto e para a produção de leite (305 dias) entre embriões produzidos in vitro do que entre doadoras ou entre a população geral. O terceiro estudo examinou os efeitos do coeficiente de endogamia da doadora, do reprodutor (usado na fertilização in vitro) e dos embriões sobre resultados de produção in vitro de embriões na raça Guzerá. Foi detectado efeito da endogamia da doadora e dos embriões sobre as características estudadas. O quarto (e último) estudo foi elaborado para comparar a adequação de modelos mistos lineares e generalizados sob método de Máxima Verossimilhança Restrita (REML) e sua adequação a variáveis discretas. Quatro modelos hierárquicos assumindo diferentes distribuições para dados de contagem encontrados no banco. Inferência foi realizada com base em diagnósticos de resíduo e comparação de razões entre componentes de variância para os modelos em cada variável. Modelos Poisson superaram tanto o modelo linear (com e sem transformação da variável) quanto binomial negativo à qualidade do ajuste e capacidade preditiva, apesar de claras diferenças observadas na distribuição das variáveis. Entre os modelos testados, a pior qualidade de ajuste foi obtida para o modelo linear mediante transformação logarítmica (Log10 X +1) da variável resposta.

Obesidade e genes candidatos: estudo de associação em populações quilombolas do Vale do Ribeira-SP

A obesidade comum é atualmente um dos problemas de saúde pública mais importante no mundo, frequentemente associada a outros distúrbios tais como hipertensão, diabetes, doenças cardiovasculares e câncer. Apesar da alta prevalência de obesidade em diversas populações, muitos dos estudos relacionados aos seus fatores de risco genéticos foram realizados com indivíduos de ascendência europeia ou asiática, mas foram poucos os realizados com populações de origem africana ou nativas americanas. Nosso trabalho tem por objetivo geral investigar potenciais fatores de risco genéticos associados ao sobrepeso e à obesidade em populações afrodescendentes remanescentes de quilombos do Vale do Ribeira - SP, comunidades rurais semi-isoladas, previamente bem caracterizadas do ponto de vista clínico, genealógico e genético-populacional. Nossa amostra constituiu-se de 759 indivíduos, pertencentes a doze populações de remanescentes de quilombos (Abobral, São Pedro, Galvão, Ivaporunduva, Pedro Cubas, André Lopes, Nhunguara, Sapatu, Pilões, Maria Rosa, Poça e Reginaldo), dos quais foram obtidos amostras de DNA, dados clínicos, informações genealógicas e medidas antropométricas. A investigação dos fatores de risco genéticos associados ao sobrepeso/obesidade foi realizada por duas abordagens: (1) estudo de associação baseado em famílias (N = 584, 59 famílias) e (2) estudo de associação populacional com indivíduos não aparentados (N=305). Foram selecionados para estudo nove polimorfismos em oito genes candidatos: LEP rs2167270, LEPR rs1137101, ADRB2 rs1042713, PPARG rs1801282, PLIN1 rs2289487, RETN rs1862513, INSIG2 rs7566605, FTO rs1121980 e FTO rs1421085. As análises de associação baseadas em família indicaram que, nessas populações, apenas o polimorfismo PLIN1 rs2289487 está associado significativamente com o grupo de risco em relação à razão cintura-quadril (RCQ >=0,85 para mulheres e >=0,90 para homens; P=0,013). Aparentemente não existem trabalhos anteriores que verificaram a associação deste polimorfismo com a obesidade por essa metodologia. As análises do estudo populacional com indivíduos não aparentados mostraram associação significativa entre: (i) o alelo G no polimorfismo LEPR rs1137101 e a variação do índice de massa corporal (IMC; P=0,027); (ii) o alelo G do polimorfismo LEPR rs1137101 e o fenótipo de sobrepeso/obesidade (IMC>=25 Kg/m²; P=0,027); (iii) o alelo G no polimorfismo ADRB2 rs1042713 e o fenótipo de risco (IMC>=25 Kg/m²; P=0,029); (iv) o polimorfismo PLIN1 rs2289487 (genótipo GG) e os menores valores do IMC (P=0,025); (v) o polimorfismo FTO rs1121980 (alelo G) e o fenótipo de risco (IMC>=25 Kg/m²), assim como a variação do IMC (P=0,037 e P=0,022 respectivamente); e (vi) o alelo A no polimorfismo FTO rs1421085 e maiores valores da circunferência da cintura (Cc; P=0,016) e da razão cintura-quadril (RCQ; P=0,030). Tomados em conjunto, nossos resultados sugerem a participação dos genes LEP, LEPR, ADRB2, PLIN1 e FTO no aumento da predisposição ao sobrepeso e à obesidade nas populações remanescentes de quilombos. Por fim, as elevadas estimativas de herdabilidade dos três fenótipos investigados (IMC=33%, Cc=33% e RCQ=70%) reforçam a relevância do papel dos fatores genéticos no acúmulo de gordura corporal. O trabalho apresentado é resultado de uma investigação cuidadosa sobre os componentes genéticos associados à regulação do peso corporal em uma população brasileira afrodescendente (com características históricas, ambientais e genéticas peculiares), corroborando a hipótese de que a obesidade comum nas populações quilombolas do Vale do Ribeira é condicionada por um mecanismo poligênico modulado por fatores ambientais importantes como o sedentarismo e a transição nutricional

Association of secondary glioblastoma and pituitary adenoma : case report

Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2014

Recommendations for Genetic Testing to Reduce the Incidence of Anthracycline-induced Cardiotoxicity

AIM Anthracycline-induced cardiotoxicity (ACT) occurs in 57% of treated patients and remains an important limitation of anthracycline-based chemotherapy. In various genetic association studies, potential genetic risk markers for ACT have been identified. Therefore, we developed evidence-based clinical practice recommendations for pharmacogenomic testing to further individualize therapy based on ACT risk. METHODS We followed a standard guideline development process; including a systematic literature search, evidence synthesis and critical appraisal, and the development of clinical practice recommendations with an international expert group. RESULTS RARG rs2229774, SLC28A3 rs7853758 and UGT1A6 rs17863783 variants currently have the strongest and the most consistent evidence for association with ACT. Genetic variants in ABCC1, ABCC2, ABCC5, ABCB1, ABCB4, CBR3, RAC2, NCF4, CYBA, GSTP1, CAT, SULT2B1, POR, HAS3, SLC22A7, SCL22A17, HFE and NOS3 have also been associated with ACT, but require additional validation. We recommend pharmacogenomic testing for the RARG rs2229774 (S427L), SLC28A3 rs7853758 (L461L) and UGT1A6*4 rs17863783 (V209V) variants in childhood cancer patients with an indication for doxorubicin or daunorubicin therapy (Level B - moderate). Based on an overall risk stratification, taking into account genetic and clinical risk factors, we recommend a number of management options including increased frequency of echocardiogram monitoring, follow-up, as well as therapeutic options within the current standard of clinical practice. CONCLUSIONS Existing evidence demonstrates that genetic factors have the potential to improve the discrimination between individuals at higher and lower risk of ACT. Genetic testing may therefore support both patient care decisions and evidence development for an improved prevention of ACT.

Novel multiple sclerosis susceptibility loci implicated in epigenetic regulation.

We conducted a genome-wide association study (GWAS) on multiple sclerosis (MS) susceptibility in German cohorts with 4888 cases and 10,395 controls. In addition to associations within the major histocompatibility complex (MHC) region, 15 non-MHC loci reached genome-wide significance. Four of these loci are novel MS susceptibility loci. They map to the genes L3MBTL3, MAZ, ERG, and SHMT1. The lead variant at SHMT1 was replicated in an independent Sardinian cohort. Products of the genes L3MBTL3, MAZ, and ERG play important roles in immune cell regulation. SHMT1 encodes a serine hydroxymethyltransferase catalyzing the transfer of a carbon unit to the folate cycle. This reaction is required for regulation of methylation homeostasis, which is important for establishment and maintenance of epigenetic signatures. Our GWAS approach in a defined population with limited genetic substructure detected associations not found in larger, more heterogeneous cohorts, thus providing new clues regarding MS pathogenesis.

Australian data and meta-analysis lend support for alpha-synuclein (NACP-Rep1) as a risk factor for Parkinson's disease

It remains unclear whether genetic variants in SNCA (the alpha-synuclein gene) alter risk for sporadic Parkinson's disease (PD). The polymorphic mixed sequence repeat (NACP-Rep I) in the promoter region of SNCA has been previously examined as a potential susceptibility factor for PD with conflicting results. We report genotype and allele distributions at this locus from 369 PD cases and 370 control subjects of European Australian ancestry, with alleles designated as -1, 0, +1, +2, and +3 as previously described. Allele frequencies designated (0) were less common in Australian cases compared to controls (OR = 0.80, 95% CI 0.62-1.03). Combined analysis including all previously published ancestral European Rep1 data yielded a highly significant association between the 0 allele and a reduced risk for PD (OR = 0.79, 95% CI 0.70-0.89, p = 0.0001). Further study must now proceed to examine in detail this interesting and biologically plausible genetic association. (C) 2004 Elsevier Ireland Ltd. All rights reserved.

New concepts for distinguishing the hidden patterns of linkage disequilibrium which underlie association between genotypes and complex phenotypes

A disappointing feature of conventional methods for detecting association between DNA variation and a phenotype of interest is that they tell us little about the hidden pattern of linkage disequilibrium (LD) with the functional variant that is actually responsible for the association. This limitation applies to case-control studies and also to the transmission/disequilibrium test (TDT) and other family-based association methods. Here we present a fresh perspective on genetic association based on two novel concepts called 'LD squares' and 'equi-risk alleles'. These describe and characterize the different patterns of gametic LD which underlie genetic association. These concepts lead to a general principle - the Equi-Risk Allele Segregation Principle - which captures the way in which underlying LD patterns affect the transmission patterns of genetic variants associated with a phenotype. This provides a basis for distinguishing the hidden LD patterns and might help to locate the functional variants responsible for the association.

Maternal alcohol use disorder and offspring ADHD: disentangling genetic and environmental effects using a children-of-twins design

Background. Children of alcoholics are significantly more likely to experience high-risk environmental exposures, including prenatal substance exposure, and are more likely to exhibit externalizing problems [e.g. attention deficit hyperactivity disorder (ADHD)]. While there is evidence that genetic influences and prenatal nicotine and/or alcohol exposure play separate roles in determining risk of ADHD, little has been done on determining the joint roles that genetic risk associated with maternal alcohol use disorder (AUD) and prenatal risk factors play in determining risk of ADHD. Method. Using a children-of-twins design, diagnostic telephone interview data from high-risk families (female monozygotic and dizygotic twins concordant or discordant for AUD as parents) and control families targeted from a large Australian twin cohort were analyzed using logistic regression models. Results. Offspring of twins with a history of AUD, as well as offspring of non-AUD monozygotic twins whose co-twin had AUD, were significantly more likely to exhibit ADHD than offspring of controls. This pattern is consistent with a genetic explanation for the association between maternal AUD and increased offspring risk of ADHD. Adjustment for prenatal smoking, which remained significantly predictive, did not remove the significant genetic association between maternal AUD and offspring ADHD. Conclusions. While maternal smoking during pregnancy probably contributes to the association between maternal AUD and offspring ADHD risk, the evidence for a significant genetic correlation suggests: (i) pleiotropic genetic effects, with some genes that influence risk of AUD also influencing vulnerability to ADHD; or (ii) ADHD is a direct risk-factor for AUD.

Identification of the semaphorin receptor PLXNA2 as a candidate for susceptibility to schizophrenia

The discovery of genetic factors that contribute to schizophrenia susceptibility is a key challenge in understanding the etiology of this disease. Here, we report the identification of a novel schizophrenia candidate gene on chromosome 1q32, plexin A2 (PLXNA2), in a genome-wide association study using 320 patients with schizophrenia of European descent and 325 matched controls. Over 25 000 single-nucleotide polymorphisms (SNPs) located within approximately 14 000 genes were tested. Out of 62 markers found to be associated with disease status, the most consistent finding was observed for a candidate locus on chromosome 1q32. The marker SNP rs752016 showed suggestive association with schizophrenia (odds ratio (OR) = 1.49, P = 0.006). This result was confirmed in an independent case control sample of European Americans (combined OR = 1.38, P = 0.035) and similar genetic effects were observed in smaller subsets of Latin Americans (OR = 1.26) and Asian Americans (OR = 1.37). Supporting evidence was also obtained from two family-based collections, one of which reached statistical significance (OR = 2.2, P = 0.02). High-density SNP mapping showed that the region of association spans approximately 60 kb of the PLXNA2 gene. Eight out of 14 SNPs genotyped showed statistically significant differences between cases and controls. These results are in accordance with previous genetic findings that identified chromosome 1q32 as a candidate region for schizophrenia. PLXNA2 is a member of the transmembrane semaphorin receptor family that is involved in axonal guidance during development and may modulate neuronal plasticity and regeneration. The PLXNA2 ligand semaphorin 3A has been shown to be upregulated in the cerebellum of individuals with schizophrenia. These observations, together with the genetic results, make PLXNA2 a likely candidate for the 1q32 schizophrenia susceptibility locus.

PCSK6 is associated with handedness in individuals with dyslexia

Approximately 90% of humans are right-handed. Handedness is a heritable trait, yet the genetic basis is not well understood. Here we report a genome-wide association study for a quantitative measure of relative hand skill in individuals with dyslexia [reading disability (RD)]. The most highly associated marker, rs11855415 (P = 4.7 × 10-7), is located within PCSK6. Two independent cohorts with RD show the same trend, with the minor allele conferring greater relative right-hand skill. Meta-analysis of all three RD samples is genome-wide significant (n = 744, P = 2.0 × 10-8). Conversely, in the general population (n = 2666), we observe a trend towards reduced laterality of hand skill for the minor allele (P = 0.0020). These results provide molecular evidence that cerebral asymmetry and dyslexia are linked. Furthermore, PCSK6 is a protease that cleaves the left–right axis determining protein NODAL. Functional studies of PCSK6 promise insights into mechanisms underlying cerebral lateralization and dyslexia.

The handedness-associated PCSK6 locus spans an intronic promoter regulating novel transcripts

We recently reported the association of the PCSK6 gene with handedness through a quantitative genome-wide association study (GWAS; P < 0.5 × 10(-8)) for a relative hand skill measure in individuals with dyslexia. PCSK6 activates Nodal, a morphogen involved in regulating left-right body axis determination. Therefore, the GWAS data suggest that the biology underlying the patterning of structural asymmetries may also contribute to behavioural laterality, e.g. handedness. The association is further supported by an independent study reporting a variable number tandem repeat (VNTR) within the same PCSK6 locus to be associated with degree of handedness in a general population cohort. Here, we have conducted a functional analysis of the PCSK6 locus combining further genetic analysis, in silico predictions and molecular assays. We have shown that the previous GWAS signal was not tagging a VNTR effect, suggesting that the two markers have independent effects. We demonstrated experimentally that one of the top GWAS-associated markers, rs11855145, directly alters the binding site for a nuclear factor. Furthermore, we have shown that the predicted regulatory region adjacent to rs11855415 acts as a bidirectional promoter controlling the expression of novel RNA transcripts. These include both an antisense long non-coding RNA (lncRNA) and a short PCSK6 isoform predicted to be coding. This is the first molecular characterization of a handedness-associated locus that supports the role of common variants in non-coding sequences in influencing complex phenotypes through gene expression regulation.

Relação do polimorfismo BDNF val66met e níveis periféricos de BDNF com a doença de Parkinson e sua sintomatologia

Neurodegenerative diseases are frequently studied due to the increasing number of cases associated with the populational ageing and to the impact on the conditions on the quality of life. Parkinson’s disease (DP) is the second most frequent neurodegenerative disease. Despite the fact that its etiology is not completely understood, it is known that DP is caused by environmental and genetic factors. Thus, the investigation of etiologic factors and mechanisms responsible for the changes that lead to DP may help early diagnostic and prevention. A possible association between DP and the common polymorphism of Brain Derived Neurotrophic Factor (BDNF) G196A (Val66Met) has been suggested by different studies with contrasting results. For this reason, the aim of this study is to investigate if the BDNF Val66Met polymorphism is related to susceptibility to DP in a cohort of Brazilian patients. Additionaly, we verify if the presence of the polymorphism implies in alterations in the BDNF whole blood concentrations, as well as variations in symptomatology. The sample comprised Brazilian patients accompanied by the neurology service of the Onofre Lopes University Hospital (HUOL) and healthy controls (CTRL). The motor aspects of DP were evaluated by Hoehn e Yahr Scale (HY), Unified Parkinson’s Disease Rating Scale (UPDRS) and Schwab & England Scale (SE). For the evaluation of non-motor symptoms were used the following instruments: Frontal Assessment Battery (BAF), Mini-Mental State Examination (MEEM), Beck Depression Inventory (IDB) and the Beck Anxiety Inventory (IAB). Blood samples were collected for BDNF Val66Met polymorphism genotyping and BDNF whole blood measurement. As expected, DP patients performed worse in motor, cognitive and emotional battery of questionnaires. Alleles distribution between DP and CTRL was not significantly different, but the A/G genotype was significantly associated with a protector factor for DP. In contrast, the G/G genotype was significantly associated with depression and anxiety development in DP patients. However, BDNF concentrations were not different between genotypes or groups. This is the first study of genetic association of this polymorphism with DP in Brazilian subjects and the first one that associate A/G genotype with protection against DP.

Further evidence for a parent-of-origin effect at the NOP9 locus on language-related phenotypes

Background - Specific language impairment (SLI) is a common neurodevelopmental disorder, observed in 5–10 % of children. Family and twin studies suggest a strong genetic component, but relatively few candidate genes have been reported to date. A recent genome-wide association study (GWAS) described the first statistically significant association specifically for a SLI cohort between a missense variant (rs4280164) in the NOP9 gene and language-related phenotypes under a parent-of-origin model. Replications of these findings are particularly challenging because the availability of parental DNA is required. Methods - We used two independent family-based cohorts characterised with reading- and language-related traits: a longitudinal cohort (n = 106 informative families) including children with language and reading difficulties and a nuclear family cohort (n = 264 families) selected for dyslexia. Results - We observed association with language-related measures when modelling for parent-of-origin effects at the NOP9 locus in both cohorts: minimum P = 0.001 for phonological awareness with a paternal effect in the first cohort and minimum P = 0.0004 for irregular word reading with a maternal effect in the second cohort. Allelic and parental trends were not consistent when compared to the original study. Conclusions - A parent-of-origin effect at this locus was detected in both cohorts, albeit with different trends. These findings contribute in interpreting the original GWAS report and support further investigations of the NOP9 locus and its role in language-related traits. A systematic evaluation of parent-of-origin effects in genetic association studies has the potential to reveal novel mechanisms underlying complex traits.

The Genetics of Success: How Single-Nucleotide Polymorphisms Associated With Educational Attainment Relate to Life-Course Development.

A previous genome-wide association study (GWAS) of more than 100,000 individuals identified molecular-genetic predictors of educational attainment. We undertook in-depth life-course investigation of the polygenic score derived from this GWAS using the four-decade Dunedin Study (N = 918). There were five main findings. First, polygenic scores predicted adult economic outcomes even after accounting for educational attainments. Second, genes and environments were correlated: Children with higher polygenic scores were born into better-off homes. Third, children's polygenic scores predicted their adult outcomes even when analyses accounted for their social-class origins; social-mobility analysis showed that children with higher polygenic scores were more upwardly mobile than children with lower scores. Fourth, polygenic scores predicted behavior across the life course, from early acquisition of speech and reading skills through geographic mobility and mate choice and on to financial planning for retirement. Fifth, polygenic-score associations were mediated by psychological characteristics, including intelligence, self-control, and interpersonal skill. Effect sizes were small. Factors connecting DNA sequence with life outcomes may provide targets for interventions to promote population-wide positive development.