Caffeine-related genes influence anxiety disorders in children and adults with ADHD.

Attention-deficit/hyperactivity disorder (ADHD) and anxiety disorders (AD) frequently co-occur, increasing morbidity and challenging treatment. Caffeine is a central nervous system stimulant and acts in the brain through adenosine receptors, influencing attention, alertness, and anxiety. In the present study, we performed a gene-set analysis to verify if genes related to caffeine response are associated with anxiety disorders in 240 children and 406 adults with ADHD. We demonstrated an association between the gene-set with AD in children (P = 0.0054) and with the number of anxiety disorders in adults (P = 0.0197). In order to test if this effect is a result of anxiety in general or is related to AD comorbid with ADHD, we evaluated the association between caffeine gene-set with AD in an adult control sample. The gene-set was neither associated with the AD presence (P = 0.3008) nor with the number of AD (P = 0.5594) in this control sample. We also test this gene set with ADHD (n = 55,374) and AD (n = 18,186) GWAS summary statistics, and we did not observe significant results with ADHD (P = 0.5587) or AD (P = 0.3930). These findings suggest the caffeine-related genes play a role in the etiology of an anxiety disorder phenotype present in children and adults with ADHD.

Host genetics influences the relationship between the gut microbiome and psychiatric disorders.

The gut microbiome is associated with psychiatric disorders; however, the molecular mechanisms mediating this association are poorly understood. The ability of host genetics to modulate the gut microbiome may be an important factor in understanding the association. In this study, we aimed to evaluate the role of genetic variants associated with the gut microbiome in the susceptibility of individuals to four psychiatric disorders: schizophrenia (SCZ), attention-deficit/hyperactivity disorder (ADHD), autism spectrum disorder (ASD), and major depressive disorder (MDD). A total of 201 host genetic markers associated with microbiome outcomes and reported in available genome-wide association studies (GWAS) were included in the analyses. We searched for these variants in the summary statistics of the largest GWAS on these disorders to date, which were published by the Psychiatric Genomic Consortium, and performed gene-based and gene set association analyses. Two variants were significantly associated with ASD (rs9401458 and rs9401452) and one with MDD (rs75036654). For the gene-based association analysis, eight genes were associated with SCZ (ASIC2, KCND3, ITSN1, SIPA1L3, RBMS3, BANK1, CSMD1, and LHFPL3), one with MDD (ACTL8), two with ADHD (C14orf39 and FBXL17), and one with ASD (PINX). The gene set comprising 83 genes was associated with SCZ (p = 0.047). These findings suggest that genes related to microbiome composition may affect the susceptibility of individuals to psychiatric disorders, mainly schizophrenia. Although less robust, the associations with ASD, ADHD, and MDD cannot be discarded.

Diet-gene interaction: effects of polymorphisms in the ACE, AGT and BDKRB2 genes and the consumption of sodium, potassium, calcium, and magnesium on blood pressure of normotensive adult individuals.

Functional variants in genes of the renin-angiotensin (RAS) and kallikrein-kinin (KKS) systems have already been implicated in blood pressure (BP) modulation, but few studies have focused on a nutrigenetics approach. Thus, the aim of this study is to verify the effects of the interaction between genetic polymorphisms (rs4340-ACE, rs699-AGT, and rs1799722-BDKRB2) and micronutrient consumption (sodium, potassium, calcium, and magnesium) on BP values of normotensive adult individuals. The study included 335 adults, men and women, 25.5 (6.6) years old. Biochemical, anthropometric, BP measurements, and food intake data were assessed for all participants. Gene-nutrient interaction on BP outcome was tested by multiple linear regression with manual backward stepwise modeling. Our results indicated that individuals with G allele for rs699 polymorphism, in the increase of sodium and magnesium consumption, both in the genotypic model (sodium, p = 0.035; magnesium, p = 0.016) and in the dominant model (sodium, p = 0.009; magnesium, p = 0.006) had higher systolic BP (SBP) levels compared to AA homozygotes (sodium, p = 0.001; magnesium, p < 0.001). Also, individuals with the T allele for the rs1799722 polymorphism, with higher calcium intake, had significantly higher levels of SBP and diastolic BP (DBP) when compared to CC homozygotes (p = 0.037). In conclusion, our findings pointed for significant interactions between genetic polymorphisms (rs699-AGT and rs1799722-BDKRB2) and the consumption of micronutrients (sodium, magnesium, and calcium) on the BP variation. These findings contribute to the understanding of the complex mechanisms involved in BP regulation, which probable include several gene-nutrition interactions.

Obesity and ADHD: Exploring the role of body composition, BMI polygenic risk score, and reward system genes.

The association between obesity and attention-deficit hyperactivity disorder (ADHD) has been extensively reported in the literature. However, the potential mechanisms underlying this association are not completely understood. This study aimed to evaluate the association between body composition and ADHD and explore the possible genetic mechanisms involved. We used data from the 1982 Pelotas (Brazil) Birth Cohort at age 30-year follow-up (N = 3630). We first used logistic regression analysis to test whether body mass index (BMI), fat mass (FM), and fat-free mass (FFM) were associated with ADHD. We further tested the association between BMI polygenic risk score (BMI-PRS) and ADHD and the role of the genes upregulated in the reward system using a gene-set association approach. BMI (odds ratio [OR] = 1.05; 95% confidence interval [CI], 1.00-1.09; p = 0.038) and FM (OR = 1.04; 95% CI, 1.00-1.07; p = 0.043) were associated with ADHD. The BMI-PRS was associated with ADHD (using p-value threshold (PT) = 0.4; OR = 1.65; 95% CI, 1.02-2.65) at a nominal level. In gene-set analysis, the reward system genes were associated with BMI in subjects with a high BMI-PRS score, considering PT = 0.4 (p = 0.014). The results suggest that BMI genetic components, especially those genes related to the reward system, may be involved in this association.

Dopamina e comportamento alimentar: polimorfismos em receptores dopaminérgicos e fenótipos relacionados à obesidade / Dopamine and eating behavior: dopaminergic receptor polymorphisms and obesity related phenotypes

Dentre os sistemas neurais responsáveis pela ingestão dos alimentos, destaca-se a via dopaminérgica mesolímbica que, através da liberação de dopamina nos núcleos de accumbens, desperta prazer e motivação para recompensas químicas e naturais. Esta via de recompensa age através dos receptores dopaminérgicos transmembranares, que variam de DRD1 a DRD5. Desta forma, considerando os efeitos prazerosos despertados pela ingestão alimentar, é plausível que variações genéticas em genes do sistema dopaminérgico possam ter um papel na arquitetura genética da obesidade. Este estudo tem como objetivo realizar uma revisão narrativa da literatura sobre a influência de variantes genéticas nos receptores dopaminérgicos em fenótipos relacionados com a obesidade. Em conjunto, os principais achados desta revisão indicaram que os genes codificadores dos receptores DRD2 e DRD4 possam ser os mais relevantes no contexto da obesidade e fenótipos relacionados. No entanto, a obesidade é uma doença complexa e multifatorial e novos estudos são ainda necessários para uma melhor compreensão do impacto da dopamina nos desfechos relacionado à obesidade. É importante também destacar que esses efeitos podem ser específicos para subgrupos de pacientes e que outros fatores, além das variantes genéticas, devem ser considerados. (AU)

Among the neural systems responsible for food ingestion, the mesolimbic dopaminergic pathway stands out by eliciting pleasure and motivation for chemical and natural rewards through the release of dopamine in the nucleus accumbens. This reward pathway is regulated by transmembrane dopaminergic receptors, which range from DRD1 to DRD5. Thus, considering the pleasurable effects aroused by food intake, it is plausible that genetic variations in genes of the dopaminergic system may have a role in the genetic architecture of obesity. This study aims to conduct a narrative review of the literature on the influence of genetic variants of dopaminergic receptors on obesity-related phenotypes. Taken together, the main findings of this review indicated that the genes encoding the DRD2 and DRD4 receptors may be the most relevant in the context of obesity and related phenotypes. However, obesity is a complex and multifactorial disease and new studies are still being conducted to better understand the impact of dopamine on obesity-related outcomes. It is also important to note that these effects can be specific to subgroups of patients and that other factors, in addition to genetic variants, must be considered. (AU)

Lack of association between TCF7L2 gene variants and type 2 diabetes mellitus in a Brazilian sample of patients with the risk for cardiovascular disease.

OBJECTIVE: Genetic variants in the transcription factor 7-like 2 (TCF7L2) gene have been described as the most noteworthy ones regarding the type 2 diabetes mellitus (T2DM) liability. This work is aimed to evaluate the association between rs12255372 and rs7903146 polymorphisms and T2DM in patients with cardiovascular disease (CAD) risk. METHODS: A sample of six hundred and forty-seven patients that underwent the coronary angiography in a Cardiac Catheterization Lab was evaluated. The patients were investigated for the presence of T2DM and coronary stenosis. The TCF7L2 polymorphisms were genotyped by real-time PCR and the haplotype analysis was performed with the MLOCUS software. All genetic tests were carried out by considering the haplotype combinations in patients divided into three groups: 0 - carrying none disease risk allele, 1 - carrying one or two risk alleles and 2 - carrying three or four risk alleles. RESULTS: No significant associations between TCF7L2 risk haplotypes and the presence of T2DM or CAD were detected. CONCLUSIONS: Our results indicate that the TCF7L2 rs12255372 and rs7903146 polymorphisms do not influence T2DM in Brazilian patients with the high risk for CAD. Therefore, we assume that these variants may only be relevant for a specific subgroup of T2DM patients or some particular human population.

Synergistic effects between ADORA2A and DRD2 genes on anxiety disorders in children with ADHD.

The prevalence of anxiety disorders in patients with Attention Deficit/Hyperactivity Disorder (ADHD) is around 15-40%, three times higher than in the general population. The dopaminergic system, classically associated with ADHD, interacts directly with the adenosinergic system through adenosine A2A receptors (A2A) and dopamine D2 receptors (D2) forming A2A-D2 heterodimers. Both dopaminergic and adenosinergic systems are implicated in anxiety disorders. Therefore, the aims of this study were: a) to investigate the main effects of ADORA2A and DRD2 gene variants on anxiety disorders in an ADHD sample of children and adolescents; b) to test potential synergism between ADORA2A and DRD2 genes on the same outcome; c) to explore ADORA2A variants functionality using an in silico approach. The sample consists of 478 children and adolescents with ADHD and their parents, totalizing 1.239 individuals. An association between the ADORA2A rs2298383 TT genotype with the presence of anxiety disorders (P = .004) and an interaction between ADORA2A-DRD2 risk haplotypes with the same outcome (P = .005) was detected. The in silico analyses showed that rs2298383 has the highest score for regulatory function among all variants in the ADORA2A gene described up to date. Altogether, the present findings suggested that the ADORA2A gene and the interaction of ADORA2A and DRD2 genes may play a role in anxiety disorders in children and adolescents with ADHD.

Assessing causality in the association between attention-deficit/hyperactivity disorder and obesity: a Mendelian randomization study.

BACKGROUND/OBJECTIVES: Attention-deficit hyperactivity disorder (ADHD), one of the most common neurodevelopmental disorders in childhood and adolescence, is associated with obesity in observational studies. However, it is unclear whether ADHD contributes to, results from or is merely correlated with obesity. This study evaluates the presence and direction of a causal effect between ADHD and obesity. SUBJECTS/METHODS: We performed a bidirectional two-sample Mendelian randomization using summary data from consortia of genome-wide association studies to investigate if ADHD (N = 55,374) has a causal effect on body mass index (BMI) in childhood (N = 35,668) and adulthood (N = 322,154-500,000), and vice-versa. The main analysis was performed using the inverse variance weighted (IVW) method. As sensitivity analyses, we used other Mendelian randomization methods that are more robust to horizontal pleiotropy (i.e., MR-Egger, weighted mode, and penalized weighted median estimators), as well as stratified the analysis by the putative mechanisms of genetic instruments (i.e., pathways involved or not in neurological processes). RESULTS: The IVW method indicated a positive causal effect of BMI on ADHD: ß = 0.324 (95% CI 0.198 to 0.449, p < 0.001; expressed as change in ln(odds ratio) of ADHD per each additional SD unit of BMI). IVW estimates were directionally consistent with other methods. On the other hand, we did not find consistent evidence for a causal effect of ADHD genetic liability on BMI. CONCLUSIONS: The results suggested that higher BMI increases the risk of developing ADHD, but not the other way around.

A vitamin D pathway gene-gene interaction affects low-density lipoprotein cholesterol levels.

Much evidence suggests an association between vitamin D deficiency and chronic diseases such as obesity and dyslipidemia. Although genetic factors play an important role in the etiology of these diseases, only a few studies have investigated the relationship between vitamin D-related genes and anthropometric and lipid profiles. The aim of this study was to investigate the association of three vitamin D-related genes with anthropometric and lipid parameters in 542 adult individuals. We analyzed the rs2228570 polymorphism in the vitamin D receptor gene (VDR), rs2134095 in the retinoid X receptor gamma gene (RXRG) and rs7041 in the vitamin D-binding protein gene (GC). Polymorphisms were genotyped by TaqMan allelic discrimination. Gene-gene interactions were evaluated by the general linear model. The functionality of the polymorphisms was investigated using the following predictors and databases: SIFT (Sorting Intolerant from Tolerant), PolyPhen-2 (Polymorphism Phenotyping v2) and Human Splicing Finder 3. We identified a significant effect of the interaction between RXRG (rs2134095) and GC (rs7041) on low-density lipoprotein cholesterol (LDL-c) levels (P=.005). Furthermore, our in silico analysis suggested a functional role for both variants in the regulation of the gene products. Our results suggest that the vitamin D-related genes RXRG and GC affect LDL-c levels. These findings are in agreement with other studies that consistently associate vitamin D and lipid profile. Together, our results corroborate the idea that analyzing gene-gene interaction would be helpful to clarify the genetic component of lipid profile.

COMT and prenatal maternal smoking in associations with conduct problems and crime: the Pelotas 1993 birth cohort study.

Conduct problems in childhood and adolescence are significant precursors of crime and violence in young adulthood. The purpose of the current study is to test the interaction between prenatal maternal smoking and COMT Val(158)Met in conduct problems and crime in the 1993 Pelotas Birth Cohort Study. Conduct problems were assessed through the parent version of the Strengths and Difficulties Questionnaire at ages 11 and 15 years. A translated version of a confidential self-report questionnaire was used to collect criminal data at 18 years of age. Negative binomial regression analyses showed an association between prenatal maternal smoking and SDQ conduct problem scores (IRR = 1.24; 95% CI: 1.14-1.34; p < 0.001) at 11 years of age. However, no evidence was found for an association between COMT genotypes and conduct scores or for an interaction between maternal smoking and this gene in predicting conduct problems. Very similar results were obtained using the 15 years conduct scores and crime measure at age 18. Prenatal maternal smoking was associated with crime (IRR = 1.28; 95% CI: 1.09-1.48; p = 0.002) but neither COMT genotypes nor the possible interaction between gene and maternal smoking were significantly associated with crime. Replications of GxE findings across different social contexts are critical for testing the robustness of findings.

Association study of C936T polymorphism of the VEGF gene and the C242T polymorphism of the p22phox gene with diabetes mellitus type 2 and distal diabetic polyneuropathy.

Even with long­term glycemic control, diabetes mellitus type 2 (DM2) remains the predominant cause of diabetic neuropathy. Single nucleotide polymorphism (SNP) C936T of the vascular endothelial growth factor (VEGF) gene and the SNP C242T of the p22phox (CYBA) gene have been investigated in relation to DM2 and its complications. The aim of the present study was to investigate the association between these two SNPs and DM2, and also between the SNPs and the signs and symptoms of diabetic distal polyneuropathy. The DM2 group consisted of 98 individuals and the control group consisted of 104 individuals. The results demonstrated that there was no association between the different genotypes or alleles and increased risk of the disease (P>0.05). With SNP C242T, a significant association with body mass index between the CTxTT genotypes (P=0.043) was identified; and the greatest body mass indexes were among individuals with the TT genotype. An association between the degree of neuropathic symptoms and genotypic/allelic distribution of these polymorphisms was not observed. In conclusion, the investigated polymorphisms are not correlated with the risk of developing DM2.

Waist-to-height ratio (WHtR) and triglyceride to HDL-C ratio (TG/HDL-c) as predictors of cardiometabolic risk.

INTRODUCTION: The excessive concentration of fat in the abdominal region is related to a higher risk of developing cardiovascular disease (CVD). Studies have been performed to identify simple and effective indicators of abdominal obesity and associated cardiometabolic risk through the use of simple parameters such as anthropometric and biochemical measures. The Triglyceride / High-density Lipoprotein Cholesterol (TG/HDL-c) has been proposed as a more practical and easy to use atherogenic marker, along with the Waist-to-Height Ratio (WHtR), which makes a superior tool for separating cardiometabolic risk related to overweight/obesity when comparing to Body Mass Index (BMI). OBJECTIVE: To verify the applicability of the WHtR and the TG/HDL-c ratio as predictors of cardiometabolic risk. METHODS: This cross-sectional study was performed at the Department of Nutrition of the UNIVATES University Center, where the participant's anthropometric and biochemical data were collected. Statistical analysis was performed by the Statistical Package for the Social Sciences software (SPSS) 20.0, with a significance level of 5% (p < 0.05). RESULTS: A total of 498 individuals took part on this research, 77.5% female and with a mean age of 25.5 ± 6.5. A high percentage of fat was found in both men and women (19.9 ± 5.80% and 29.24 ± 5.43%, respectively). The prevalence of overweight/obesity (BMI ≥ 25Kg/m(2)) was 35.05%. The WHtR marker was significantly correlated to Low-density Lipoprotein Cholesterol (LDL-c), Triglyceride (TG) and Anthropometric BMI values, waist circumference (WC) and body fat percentage (BF%). For the TG/HDL-c ratio, there was a positive and significant correlation to the same markers, beyond TC. There was also a correlation between WHtR and TG/HDL-c, and both presented a negative and significant correlation with HDL-c. CONCLUSION: WHtR and TG/HDL-c values were found to be good markers for the cardiometabolic risk ratio in the studied sample. Several studies, original articles and academic reviews confirm the use of the WHtR or TG/HDL-c markers for that purpose in adults.

Introducción: La concentracion excesiva de grasa en la region abdominal se relaciona con un mayor riesgo de desarrollar enfermedad cardiovascular (ECV). Se han realizado estudios para identificar los indicadores simples y eficaces de la obesidad abdominal y el riesgo cardiometabolico asociados con el uso de parametros simples, como las medidas antropometricas y bioquimicas. El / alta densidad de colesterol de lipoproteinas de trigliceridos (TG / HDL-c) se ha propuesto como un enfoque mas practico y facil de usar marcador aterogenico, junto con la relacion cintura-estatura (RCEst), lo que hace que una herramienta superior para separar cardiometabolico riesgos relacionados con el sobrepeso / obesidad cuando se compara con el indice de masa corporal (IMC). Objetivo: Verificar la aplicabilidad de la RCEst y la relacion TG / HDL-c como predictores de riesgo cardiometabolico. Métodos: Este estudio transversal se llevo a cabo en el Departamento de Nutricion del Centro Universitario UNIVATES, donde se recogieron datos antropometricos y bioquimicos de los participantes. El analisis estadistico se realizo mediante el paquete estadistico para el software de Ciencias Sociales (SPSS) 20,0, con un nivel de significacion del 5% (p.

Waist-to-height ratio (WHtR) and triglyceride to HDL-c ratio (TG/HDL-c) as predictors of cardiometabolic risk / Razón cintura-estatura (RCA) y los triglicéridos en comparación con el HDL-C (TG / HDL-C): como predictores de riesgo cardiometabólico

Introduction: The excessive concentration of fat in the abdominal region is related to a higher risk of developing cardiovascular disease (CVD). Studies have been performed to identify simple and effective indicators of abdominal obesity and associated cardiometabolic risk through the use of simple parameters such as anthropometric and biochemical measures. The Triglyceride / High-density Lipoprotein Cholesterol (TG/HDL-c) has been proposed as a more practical and easy to use atherogenic marker, along with the Waist-to-Height Ratio (WHtR), which makes a superior tool for separating cardiometabolic risk related to overweight/obesity when comparing to Body Mass Index (BMI). Objective: To verify the applicability of the WHtR and the TG/HDL-c ratio as predictors of cardiometabolic risk. Methods: This cross-sectional study was performed at the Department of Nutrition of the UNIVATES University Center, where the participant’s anthropometric and biochemical data were collected. Statistical analysis was performed by the Statistical Package for the Social Sciences software (SPSS) 20.0, with a significance level of 5% (p < 0.05). Results: A total of 498 individuals took part on this research, 77.5% female and with a mean age of 25.5±6.5. A high percentage of fat was found in both men and women (19.9 ±5.80% and 29.24±5.43%, respectively). The prevalence of overweight/obesity (BMI ≥ 25Kg/m²) was 35.05%. The WHtR marker was significantly correlated to Low-density Lipoprotein Cholesterol (LDL-c), Triglyceride (TG) and Anthropometric BMI values, waist circumference (WC) and body fat percentage (BF%). For the TG/HDL-c ratio, there was a positive and significant correlation to the same markers, beyond TC. There was also a correlation between WHtR and TG/HDL-c, and both presented a negative and significant correlation with HDL-c. Conclusion: WHtR and TG/HDL-c values were found to be good markers for the cardiometabolic risk ratio in the studied sample. Several studies, original articles and academic reviews confirm the use of the WHtR or TG/ HDL-c markers for that purpose in adults (AU)

Introducción: La concentración excesiva de grasa en la region abdominal se relaciona con un mayor riesgo de desarrollar enfermedad cardiovascular (ECV). Se han realizado estudios para identificar los indicadores simples y eficaces de la obesidad abdominal y el riesgo cardiometabólico asociados con el uso de parámetros simples, como las medidas antropométricas y bioquímicas. El / alta densidad de colesterol de lipoproteínas de triglicéridos (TG / HDL-c) se ha propuesto como un enfoque mas practico y fácil de usar marcador aterogénico, junto con la relación cintura-estatura (RCEst), lo que hace que una herramienta superior para separar cardiometabólico riesgos relacionados con el sobrepeso / obesidad cuando se compara con el indice de masa corporal (IMC). Objetivo: Verificar la aplicabilidad de la RCEst y la relación TG / HDL-c como predictores de riesgo cardiometabólico. Métodos: Este estudio transversal se llevo a cabo en el Departamento de Nutrición del Centro Universitario UNIVATES, donde se recogieron datos antropométricos y bioquímicos de los participantes. El análisis estadístico se realizo mediante el paquete estadístico para el software de Ciencias Sociales (SPSS) 20,0, con un nivel de significación del 5% (p <0,05). Resultados: Un total de 498 personas participaron en esta investigación, el 77,5% de mujeres y con una edad media de 25,5 } 6,5. Un alto porcentaje de grasa se encuentra en hombres y mujeres (19,9 } 5,80% y 29,24 } 5,43%, respectivamente). La prevalencia de sobrepeso / obesidad (IMC ≥ 25 kg / m2) fue 35,05%. El marcador RCEst se correlaciono significativamente con baja densidad de colesterol de lipoproteinas (LDL-c), triglicéridos (TG) y antropométricos IMC valores, la circunferencia de la cintura (CC) y el porcentaje de grasa corporal (% GC). Para la relación TG / HDL-c, hubo una correlación positiva y significativa para los mismos marcadores, mas allá de TC. También hubo una correlación entre la RCEst y TG / HDL-c, y ambos presentaron una correlación negativa y significativa con el HDL-c. Conclusión: No se encontraron valores RCEst y TG / HDL-c para ser buenos marcadores de la razón de riesgo cardiometabólico en la muestra estudiada. Varios estudios, artículos originales y revisiones académicas confirman el uso de la RCEst o marcadores TG / HDL-c para tal fin en los adultos (AU)

Cadherin-13 gene is associated with hyperactive/impulsive symptoms in attention/deficit hyperactivity disorder.

Several efforts have been made to find new genetic risk variants which explain the high heritability of ADHD. At the genome level, genes involved in neurodevelopmental pathways were pointed as candidates. CDH13 and CTNNA2 genes are within GWAS top hits in ADHD and there are emerging notions about their contribution to ADHD pathophysiology. The main goal of this study is to test the association between SNPs in CDH13 and CTNNA2 genes and ADHD across the life cycle in subjects with ADHD. This study included 1,136 unrelated ADHD cases and 946 individuals without ADHD. No significant association between CDH13 and CTNNA2 was observed between cases and controls across different samples (P ≥ 0.096 for all comparisons). No allele was significantly more transmitted than expected from parents to ADHD probands. The CDH13 rs11150556 CC genotype was associated with more hyperactive/impulsive symptoms in youths with ADHD (children/adolescents clinical sample: F = 7.666, P = 0.006, FDR P-value = 0.032; Pelotas Birth Cohort sample: F = 6.711, P = 0.011, FDR P-value = 0.032). Although there are many open questions regarding the role of neurodevelopmental genes in ADHD symptoms, the present study suggests that CDH13 is associated with hyperactive/impulsive symptoms in youths with ADHD.

The Brazilian contribution to Attention-Deficit/Hyperactivity Disorder molecular genetics in children and adolescents.

Attention-Deficit/Hyperactivity Disorder (ADHD) is a common psychiatric condition of children worldwide. This disorder is defined by a combination of symptoms of inattention and hyperactivity/impulsivity. Diagnosis is based on a sufficient number of symptoms causing impairment in these two domains determining several problems in personal and academic life. Although genetic and environmental factors are important in ADHD etiology, how these factors influence the brain and consequently behavior is still under debate. It seems to be consensus that a frontosubcortical dysfunction is responsible, at least in part, for the ADHD phenotype spectrum. The main results from association and pharmacogenetic studies performed in Brazil are discussed. The investigations performed so far on ADHD genetics in Brazil and elsewhere are far from conclusive. New plausible biological hypotheses linked to neurotransmission and neurodevelopment, as well as new analytic approaches are needed to fully disclose the genetic component of the disorder.

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.