FARMACOGENÉTICA DE FÁRMACOS HIPOLIPEMIANTES

Although, the pharmacological treatment for cholesterol reduction has been an advance in the cardiovascular and atherosclerosis treatment, the benefits are still limited due to interindividual variability in the response to these drugs. Disease severity, treatment adhesion, physiological conditions, biological conditions as well as the patient genetic profile could be cited as important factors for the evaluation of interindividual variability. In this context, three large groups of genes could be investigated: a) Genes that codify proteins involved in metabolism and/or transport of drugs, influencing the pharmacokinetics of these compounds. b) Genes that codify proteins involved in the mechanism of action and/or in the metabolic pathway where of drug action (pharmacodynamics). c) Genes that codify proteins involved in the direct development of the disease or in intermediate phenotypes. In this revision we discussed pharmacogenetic studies of the main lipid lowering drugs, and the expectations in relation to pharmacogenetics in order to help our prediction capacity in relation to treatment efficacy as well as the possibility to reduce adverse effects of these drugs. As soon as new studies would be performed and that most of the genetic variability associated with drug action would be disclosed, the great challenge would be the application of this knowledge in practical medicine.Embora o tratamento farmacoterapêutico para redução dos níveis de colesterol tenha sido um dos grandes avanços no tratamento de doenças cardiovasculares e aterosclerose, os benefícios são ainda limitados devido a variabilidade interindividual na resposta a esses medicamentos. Entre os fatores importantes para a avaliação da variabilidade interindividual pode-se citar a severidade da doença, adesão ao tratamento, condições fisiológicas, condições biológicas e o perfil genético do paciente. Neste contexto, três grandes grupos de genes podem ser analisados: a) Genes que codificam proteínas envolvidas na metabolização e/ou transporte dos fármacos, influenciando a farmacocinética dos compostos. b) Genes que codificam proteínas envolvidas no mecanismo de ação e/ou nas rotas metabólicas em que o fármaco age (farmacodinâmica). c) Genes que codificam proteínas envolvidas no desenvolvimento direto da doença ou de fenótipos intermediários. Nessa revisão discutimos os estudos farmacogenéticos dos principais fármacos hipolipemiantes e a expectativa em relação a fármacogenética de auxiliar em nossa capacidade de predição em relação à eficácia do tratamento e a possibilidade de redução dos efeitos adversos a esses medicamentos. Na medida que novos estudos forem efetuados e que a grande parte da variabilidade genética envolvidas nas diferenças interindividuais na ação de fármacos for elucidada, o grande desafio será a aplicação desses conhecimentos na prática médica

Diversity of two short tandem repeat loci (CD4 and F13A1) in three Brazilian ethnic groups

Two microsatellites (CD4 and F13A1) were investigated in seven Brazilian populations: one group each of European- and African-derived subjects from Porto Alegre, southern Brazil, and five Amerindian tribes (three Tupi-Monde speaking [Gaviao, Surui, and Zoro], one Macro-Ge [Xavante], and one Carib [Wai-Wai]). For both markers, neo-Brazilians presented with a high diversity, but Amerindians showed a low level of variability. Genotype frequency distributions were heterogeneous among populations, the only exception being similar CD4 frequencies in Afro- and Euro-Brazilians. Gene diversity analysis revealed that most of the total variation is due to intrapopulational diversity in all populations, Because of the high information content of these markers in Afro- and Euro-Brazilians, these systems are most appropriate for forensic analyses. The comparison among Brazilian and other world populations revealed high similarity among populations of the same ethnic group, indicating a high discriminative power for these markers

Transthyretin: No association between serum levels or gene variants and schizophrenia

It has been proposed that schizophrenia results from an environmental insult in genetically predisposed individuals. Environmental factors capable of modulating transcriptional activity and their carriers could link the genetic and environmental components of schizophrenia. Among these is transthyretin (TTR), a major carrier of thyroid hormones and retinol-binding protein (RBP). Retinoids and thyroid hormones regulate the expression of several genes, both during development and in the adult brain. Decreased TTR levels have been reported in the cerebrospinal fluid of patients with depression and Alzheimer's disease, and the absence of TTR influences behavior in mice. DNA variants capable of altering TTR ability to carry its ligands, either due to reduced transcription of the gene or to structural modifications of the protein, may influence development of the central nervous system and behavior. In the present study we searched for variants in the regulatory and coding regions of the TTR gene, and measured circulating levels of TTR and RBP. We found a novel single nucleotide polymorphism (SNP), ss46566417, 18 bp upstream of exon 4. Neither this SNP nor the previously described rs1800458 were found associated with schizophrenia. In addition, serum TTR and RBP levels did not differ between mentally healthy and schizophrenic individuals. In conclusion, our data does not support an involvement of the TTR gene in the pathophysiology of schizophrenia.http://www.sciencedirect.com/science/article/B6T8T-4K12CM6-2/1/78223a224d1392e250f7562405e6796

Apolipoprotein B signal peptide polymorphism distribution among South Amerindian populations

This is the published version, also available here: http://www.jstor.org/stable/41465798

The Genomic Ancestry of Individuals from Different Geographical Regions of Brazil Is More Uniform Than Expected

Based on pre-DNA racial/color methodology, clinical and pharmacological trials have traditionally considered the different geographical regions of Brazil as being very heterogeneous. We wished to ascertain how such diversity of regional color categories correlated with ancestry. Using a panel of 40 validated ancestry-informative insertion-deletion DNA polymorphisms we estimated individually the European, African and Amerindian ancestry components of 934 self-categorized White, Brown or Black Brazilians from the four most populous regions of the Country. We unraveled great ancestral diversity between and within the different regions. Especially, color categories in the northern part of Brazil diverged significantly in their ancestry proportions from their counterparts in the southern part of the Country, indicating that diverse regional semantics were being used in the self-classification as White, Brown or Black. To circumvent these regional subjective differences in color perception, we estimated the general ancestry proportions of each of the four regions in a form independent of color considerations. For that, we multiplied the proportions of a given ancestry in a given color category by the official census information about the proportion of that color category in the specific region, to arrive at a “total ancestry” estimate. Once such a calculation was performed, there emerged a much higher level of uniformity than previously expected. In all regions studied, the European ancestry was predominant, with proportions ranging from 60.6% in the Northeast to 77.7% in the South. We propose that the immigration of six million Europeans to Brazil in the 19th and 20th centuries - a phenomenon described and intended as the “whitening of Brazil” - is in large part responsible for dissipating previous ancestry dissimilarities that reflected region-specific population histories. These findings, of both clinical and sociological importance for Brazil, should also be relevant to other countries with ancestrally admixed populations

A genetic investigation of sex bias in the prevalence of attention-deficit/hyperactivity disorder

Background Attention-deficit/hyperactivity disorder (ADHD) shows substantial heritability and is 2-7 times more common in males than females. We examined two putative genetic mechanisms underlying this sex bias: sex-specific heterogeneity and higher burden of risk in female cases. Methods We analyzed genome-wide autosomal common variants from the Psychiatric Genomics Consortium and iPSYCH Project (20,183 cases, 35,191 controls) and Swedish populationregister data (N=77,905 cases, N=1,874,637 population controls). Results Genetic correlation analyses using two methods suggested near complete sharing of common variant effects across sexes, with rg estimates close to 1. Analyses of population data, however, indicated that females with ADHD may be at especially high risk of certain comorbid developmental conditions (i.e. autism spectrum disorder and congenital malformations), potentially indicating some clinical and etiological heterogeneity. Polygenic risk score (PRS) analysis did not support a higher burden of ADHD common risk variants in female cases (OR=1.02 [0.98-1.06], p=0.28). In contrast, epidemiological sibling analyses revealed that the siblings of females with ADHD are at higher familial risk of ADHD than siblings of affected males (OR=1.14, [95% CI: 1.11-1.18], p=1.5E-15). Conclusions Overall, this study supports a greater familial burden of risk in females with ADHD and some clinical and etiological heterogeneity, based on epidemiological analyses. However, molecular genetic analyses suggest that autosomal common variants largely do not explain the sex bias in ADHD prevalence