Sandra López-León

Meta-analysis of six genes (BDNF, DRD1, DRD3, DRD4, GRIN2B and MAOA) involved in neuroplasticity and the risk for alcohol dependence.

BACKGROUND Alcohol-related problems have a large impact on human health, accounting for around 4% of deaths and 4.5% of disability-adjusted life-years around the world. Genetic factors could explain a significant fraction of the risk for alcohol dependence (AD). Recent meta-analyses have found significant pooled odds ratios (ORs) for variants in the ADH1B, ADH1C, DRD2 and HTR2A genes. METHODS In the present study, we carried out a meta-analysis of common variants in 6 candidate genes involved in neurotransmission and neuroplasticity: BDNF, DRD1, DRD3, DRD4, GRIN2B and MAOA. We carried out a systematic search for published association studies that analyzed the genes of interest. Relevant articles were retrieved and demographic and genetic data were extracted. Pooled ORs were calculated using a random-effects model using the Meta-Analyst program. Dominant, recessive and allelic models were tested and analyses were also stratified by ethnicity. RESULTS Forty two published studies were included in the current meta-analysis: BDNF-rs6265 (nine studies), DRD1-rs4532 (four studies), DRD3-rs6280 (eleven studies), DRD4-VNTR (seven studies), GRIN2B-rs1806201 (three studies) and MAOA-uVNTR (eight studies). We did not find significant pooled ORs for any of the six genes, under different models and stratifying for ethnicity. CONCLUSIONS In terms of the number of candidate genes included, this is one of the most comprehensive meta-analyses for genetics of AD. Pooled ORs did not support consistent associations with any of the six candidate genes tested. Future studies of novel genes of functional relevance and meta-analyses of quantitative endophenotypes could identify further susceptibility molecular factors for AD.

A functional polymorphism in the promoter region of MAOA gene is associated with daytime sleepiness in healthy subjects

Excessive daytime sleepiness (EDS) is one of the main causes of car and industrial accidents and it is associated with increased morbidity and alterations in quality of life. Prevalence of EDS in the general population around the world ranges from 6.2 to 32.4%, with a heritability of 38-40%. However, few studies have explored the role of candidate genes in EDS. Monoamine oxidase A (MAOA) gene has an important role in the regulation of neurotransmitter levels and a large number of human behaviors. We hypothesized that a functional VNTR in the promoter region of the MAOA gene might be associated with daytime sleepiness in healthy individuals. The Epworth sleepiness scale (ESS) was applied to 210 Colombian healthy subjects (university students), which were genotyped for MAOA-uVNTR. MAOA-uVNTR showed a significant association with ESS scores (p = 0.01): 3/3 genotype carriers had the lowest scores. These results were supported by differences in MAOA-uVNTR frequencies between diurnal somnolence categories (p = 0.03). Our finding provides evidence for the first time that MAOA-uVNTR has a significant association with EDS in healthy subjects. Finally, these data suggest that functional variations in MAOA gene could have a role in other phenotypes of neuropsychiatric relevance.

Study of a Functional Polymorphism in the PER3 Gene and Diurnal Preference in a Colombian Sample

Polymorphisms in human clock genes have been evaluated as potential factors influencing circadian phenotypes in several populations. There are conflicting results for the association of a VNTR in the PER3 gene and diurnal preference in different studies. The objective of this study was to investigate the association between diurnal preference and daytime somnolence with the PER3 VNTR polymorphism (rs57875989) in healthy subjects from Colombia, a Latin American population.A total of 294 undergraduate university students from Bogotá, Colombia participated in this study. Two validated self-report questionnaires, the Composite Scale of Morningness (CSM) and the Epworth Sleep Scale (ESS) were used to assess diurnal preference and daytime somnolence, respectively. Individuals were genotyped for the PER3 VNTR using conventional PCR. Statistical comparisons were carried out with PLINK and SNPStats programs. The PER3 VNTR polymorphism was not associated with either diurnal preference or daytime somnolence in this population. No significant differences in mean scores for those scales were found between PER3 VNTR genotypes. In addition, there were no differences in allelic or genotypic frequencies between chronotype categories. This is consistent with several negative findings in other populations, indicating that the proposed influence of this polymorphism in diurnal preference, and related endophenotypes of neuropsychiatric importance, needs further clarification. This is the first report of molecular genetics of human circadian phenotypes in a Spanish-speaking population.

Cardiovascular safety of vildagliptin in patients with type 2 diabetes: A European multi-database, non-interventional post-authorization safety study

The aim of this non‐interventional, multi‐database, analytical cohort study was to assess the cardiovascular (CV) safety of vildagliptin vs other non‐insulin antidiabetic drugs (NIADs) using real‐world data from 5 European electronic healthcare databases. Patients with type 2 diabetes aged ≥18 years on NIAD treatment were enrolled. Adjusted incidence rate ratios (IRRs) and 95% confidence intervals (CIs) for the outcomes of interest (myocardial infarction [MI], acute coronary syndrome [ACS], stroke, congestive heart failure [CHF], individually and as a composite) were estimated using negative binomial regression. Approximately 2.8% of the enrolled patients (n = 738 054) used vildagliptin at any time during the study, with an average follow‐up time of 1.4 years, resulting in a cumulative current vildagliptin exposure of 28 330 person‐years. The adjusted IRRs (vildagliptin [±other NIADs] vs other NIADs) were in the range of 0.61 to 0.97 (MI), 0.55 to 1.60 (ACS), 0.02 to 0.77 (stroke), 0.49 to 1.03 (CHF), and 0.22 to 1.02 (composite CV outcomes). The IRRs and their 95% CIs were close to 1, demonstrating no increased risk of adverse CV events, including the risk of CHF, with vildagliptin vs other NIADs in real‐world conditions.

A functional SNP in MIR124-1, a brain expressed miRNA gene, is associated with aggressiveness in a Colombian sample.

BACKGROUND Interpersonal violence and suicide are among the main causes of mortality and morbidity around the world. In several developing countries, such as Colombia, they are among the first five entities of public health concern. Aggressiveness is an important endophenotype for aggression and suicidal behavior, having a heritability of around 50%. Exploration of classical candidate genes, involved in serotoninergic and dopaminergic neurotransmission, has identified few consistent risk factors for aggressiveness. miRNAs are a novel class of molecules with a growing role in normal neural function and neuropsychiatric disorders; of special interest, miR-124 is a brain-specific miRNA that is key for neuronal plasticity. We evaluated the hypothesis that a functional polymorphism in MIR124-1 gene might be associated with aggressiveness in a Colombian sample. METHODS The Spanish adaptation of the refined version of the Aggression Questionnaire and the abbreviated Barratt Impulsiveness Scale were applied to 170 young subjects. The functional SNP in MIR124-1 (rs531564) was genotyped by a TaqMan assay. RESULTS We found a significant association between the MIR124-1 and aggressiveness in our sample, with G/G carriers having lower scores (P=0.01). This association seemed to be specific for aggressiveness, as it was not significant for impulsiveness. CONCLUSIONS We showed for the first time the association of a functional polymorphism in MIR124-1 and aggressiveness. Known targets of miR-124 (such as BDNF and DRD4 genes) could explain the effect of this miRNA on behavior. A future analysis of additional novel functional polymorphisms in other brain expressed miRNAs could be useful for a deeper understanding of aggression in humans.

APOE gene and neuropsychiatric disorders and endophenotypes: A comprehensive review

The Apolipoprotein E (APOE) gene is one of the main candidates in neuropsychiatric genetics, with hundreds of studies carried out in order to explore the possible role of polymorphisms in the APOE gene in a large number of neurological diseases, psychiatric disorders, and related endophenotypes. In the current article, we provide a comprehensive review of the structural and functional aspects of the APOE gene and its relationship with brain disorders. Evidence from genome‐wide association studies and meta‐analyses shows that the APOE gene has been significantly associated with several neurodegenerative disorders. Cellular and animal models show growing evidence of the key role of APOE in mechanisms of brain plasticity and behavior. Future analyses of the APOE gene might find a possible role in other neurological diseases and psychiatric disorders and related endophenotypes.

Sports genetics: the PPARA gene and athletes’ high ability in endurance sports. A systematic review and meta-analysis

A meta-analysis was performed with the aim of re-evaluating the role of the peroxisome proliferator activated receptor alpha (PPARA) gene intron 7 G/C polymorphism (rs4253778) in athletes’ high ability in endurance sports. Design: A meta-analysis of case control studies assessing the association between the G/C polymorphisms of the PPARA gene and endurance sports was conducted. The Cochrane Review Manager software was used to compare the genotype and allele frequencies between endurance athletes and controls to determine whether a genetic variant is more common in athletes than in the general population. Five studies, encompassing 760 endurance athletes and 1792 controls, fulfilled our inclusion criteria. The pooled odds ratio (and confidence intervals, CIs) for the G allele compared to the C allele was 1.65 (95% CI 1.39-1.96). The pooled OR for the GG genotype compared to the GC genotype was 1.79 (95% CI 1.44-2.22), and for the GG genotype compared to the CC genotype 2.37 (95% CI 1.40-3.99). There was no evidence of heterogeneity (I2 =0%) or of publication bias. Athletes with high ability in endurance sports had a higher frequency of the GG genotype and G allele.

No Association of BDNF, COMT, MAOA, SLC6A3, and SLC6A4 Genes and Depressive Symptoms in a Sample of Healthy Colombian Subjects.

Background. Major depressive disorder (MDD) is the second cause of years lived with disability around the world. A large number of studies have been carried out to identify genetic risk factors for MDD and related endophenotypes, mainly in populations of European and Asian descent, with conflicting results. The main aim of the current study was to analyze the possible association of five candidate genes and depressive symptoms in a Colombian sample of healthy subjects. Methods and Materials. The Spanish adaptation of the Hospital Anxiety and Depression Scale (HADS) was applied to one hundred eighty-eight healthy Colombian subjects. Five functional polymorphisms were genotyped using PCR-based assays: BDNF-Val66Met (rs6265), COMT-Val158Met (rs4680), SLC6A4-HTTLPR (rs4795541), MAOA-uVNTR, and SLC6A3-VNTR (rs28363170). Result. We did not find significant associations with scores of depressive symptoms, derived from the HADS, for any of the five candidate genes (nominal p values >0.05). In addition, we did not find evidence of significant gene-gene interactions. Conclusion. This work is one of the first studies of candidate genes for depressive symptoms in a Latin American sample. Study of additional genetic and epigenetic variants, taking into account other pathophysiological theories, will help to identify novel candidates for MDD in populations around the world.

A novel cost-effective assay based on real-time PCR for COMT Val158Met genotyping

Abstract A functional polymorphism in the catechol-O-methyltransferase (COMT) gene (Val158Met) has been associated with a large number of human diseases and endophenotypes. The aim of this study was to develop a novel cost-effective assay to genotype this polymorphism. The novel assay was based on the combination of allele-specific PCR and high-resolution melting in a qPCR platform. Melt-curve analysis allowed a clear differentiation of the three genotypes. This novel assay could be implemented in the study of a large number of diseases and endophenotypes related to COMT dysfunction and could be extended for the analysis of other functional polymorphisms.

Personality traits and health-related quality of life: the mediator role of coping strategies and psychological distress

BackgroundThe study of health-related quality of life (HRQOL) is an important topic in mental health around the globe. However, there is the need for more evidence about the cumulative influence of psychological variables on HRQOL. The main aim of the study was to evaluate how specific personality traits might explain scores in HRQOL and to explore how this relationship might be mediated by coping styles and psychological distress.MethodsYoung Colombian subjects (N = 274) were included (mean age: 21.3; SD = 3.8). The Short-Form Health Survey was used to measure HRQOL. For assessment of psychological variables, the Hospital Anxiety and Depression Scale, the Zung Self-Rating Anxiety Scale, The Coping Inventory for Stressful Situations and the short version of Big Five Inventory were used.ResultsThe personality trait that was the best predictor of HRQOL was openness to experience, forming an explanatory model for HRQOL, along with emotional coping style and depressive and anxious symptoms. Emotional coping style and psychological distress were significant mediators of the relationship between openness and HRQOL.ConclusionsOur findings provide additional data about the cumulative influence of specific psychological variables on HRQOL, in a mostly young female Latin American sample.