Meta-analysis and systematic review of ADGRL3 (LPHN3) polymorphisms in ADHD susceptibility.

The gene encoding adhesion G protein-coupled receptor L3 (ADGRL3, also referred to as latrophilin 3 or LPHN3) has been associated with ADHD susceptibility in independent ADHD samples. We conducted a systematic review and a comprehensive meta-analysis to summarize the associations between the most studied ADGRL3 polymorphisms (rs6551665, rs1947274, rs1947275, and rs2345039) and both childhood and adulthood ADHD. Eight association studies (seven published and one unpublished) fulfilled criteria for inclusion in our meta-analysis. We also incorporated GWAS data for ADGRL3. In order to avoid overlapping samples, we started with summary statistics from GWAS samples and then added data from gene association studies. The results of our meta-analysis suggest an effect of ADGRL3 variants on ADHD susceptibility in children (n = 8724/14,644 cases/controls and 1893 families): rs6551665 A allele (Z score = -2.701; p = 0.0069); rs1947274 A allele (Z score = -2.033; p = 0.0421); rs1947275 T allele (Z score = 2.339; p = 0.0978); and rs2345039 C allele (Z score = 3.806; p = 0.0026). Heterogeneity was found in analyses for three SNPs (rs6551665, rs1947274, and rs2345039). In adults, results were not significant (n = 6532 cases/15,874 controls): rs6551665 A allele (Z score = 2.005; p = 0.0450); rs1947274 A allele (Z score = 2.179; p = 0.0293); rs1947275 T allele (Z score = -0.822; p = 0.4109); and rs2345039 C allele (Z score = -1.544; p = 0.1226). Heterogeneity was found just for rs6551665. In addition, funnel plots did not suggest publication biases. Consistent with ADGRL3's role in early neurodevelopment, our findings suggest that the gene is predominantly associated with childhood ADHD.

Association between DRD2 and DRD3 gene polymorphisms and gastrointestinal symptoms induced by levodopa therapy in Parkinson's disease.

Levodopa is the most used drug to treat motor symptoms in Parkinson's disease (PD). However, dopaminergic side effects such as nausea and vomiting may occur. Several evidences indicate a major role for dopamine receptors D2 (DRD2) and D3 (DRD3) in emetic activity. The aim of this study was to investigate the relationship of DRD2 rs1799732 and DRD3 rs6280 gene polymorphisms with gastrointestinal (GI) symptoms induced by levodopa in PD patients. Two hundred and seventeen PD patients on levodopa therapy were investigated. DRD2 rs1799732 and DRD3 rs6280 polymorphisms were genotyped by PCR-based methods. Multiple Poisson regression method with robust variance estimators was performed to assess the association between polymorphisms and gastrointestinal symptoms. The analyses showed that DRD2 Ins/Ins (prevalence ratio (PR)=2.374, 95% confidence interval (CI): 1.105-5.100; P=0.027) and DRD3 Ser/Ser genotypes (PR=1.677, 95% CI 1.077-2.611; P=0.022) were independent and predictors of gastrointestinal symptoms associated with levodopa therapy. Despite all the efforts to alleviate GI symptoms, this adverse effect still occurs in PD patients. Pharmacogenetic studies of GI symptoms induced by levodopa therapy have the potential to display new ways to better understand the molecular mechanisms involved in these side effects.

ESR1 polymorphisms and statin therapy: a sex-specific approach.

Lipid-lowering therapy has shown a high degree of variability in clinical response and there is evidence that the variability in drug response between individuals is due to genetic factors. Thirteen single nucleotide polymorphisms (SNPs) within the ESR1 gene were evaluated with basal lipid and lipoprotein levels, as well as response to lipid-lowering therapy, in 495 hypercholesterolemic individuals of European descent receiving simvastatin or atorvastatin. Significant associations were detected between rs4870061 (P=0.040, corrected P-value (PC)=0.440), rs1801132 (P=0.002, PC=0.022) and the SNP rs3020314 (P=0.013, PC=0.143) with triglyceride (TG) baseline levels. The rs4870061 was also associated with high-density lipoprotein cholesterol (HDL-C) baseline levels (P=0.045, PC=0.495). Regarding statin efficacy, rs2234693 C/C was associated with greater HDL-C increase (P=0.037; PC=0.407) and rs3798577 T allele was associated with greater total cholesterol (TC) reduction (P=0.019; PC=0.209) and greater TG reduction (P=0.026; PC=0.286). These associations suggest that ESR1 polymorphisms are in part responsible for the TC, HDL-C and TG variation levels and this effect may be sex-specific.

Association between HLA-DR4 haplotypes and tuberculin skin test response in the Aché population.

The human leukocyte antigen (HLA) system has a major role in the regulation of the immune response as it is involved in the defense against pathogens. Evidence for association with tuberculosis (TB) is more consistent for class II than for class I HLA genes. TB is important among indigenous peoples in South America, not only because of its historical role in regional depopulation, but also because it is still widespread. The aim of this study was to evaluate the association of HLA class II alleles, haplotypes and genotypes and tuberculin skin test response (TST) in 76 individuals of the Aché population. Poisson Regression was employed to assess risk genotypes. DRB1*04, DQA1*03 and DQB1*03:02 were associated with TST response in this population.

Association of common genetic variants of HOMER1 gene with levodopa adverse effects in Parkinson's disease patients.

Levodopa is the most effective symptomatic therapy for Parkinson's disease, but its chronic use could lead to chronic adverse outcomes, such as motor fluctuations, dyskinesia and visual hallucinations. HOMER1 is a protein with pivotal function in glutamate transmission, which has been related to the pathogenesis of these complications. This study investigates whether polymorphisms in the HOMER1 gene promoter region are associated with the occurrence of the chronic complications of levodopa therapy. A total of 205 patients with idiopathic Parkinson's disease were investigated. Patients were genotyped for rs4704559, rs10942891 and rs4704560 by allelic discrimination with Taqman assays. The rs4704559 G allele was associated with a lower prevalence of dyskinesia (prevalence ratio (PR)=0.615, 95% confidence interval (CI) 0.426-0.887, P=0.009) and visual hallucinations (PR=0.515, 95% CI 0.295-0.899, P=0.020). Our data suggest that HOMER1 rs4704559 G allele has a protective role for the development of levodopa adverse effects.

Distribution patterns of variability for 18 immune system genes in Amerindians--relationship with history and epidemiology.

Native American populations generally have a higher prevalence of infectious diseases than non-Native populations and this fact can induce different pressures in their immune system. We investigated the patterns of population differentiation (FST ) of 32 polymorphisms related to adaptive immune response in four Native American populations (Aché, Guarani-Kaiowá, Guarani-Ñandeva and Kaingang), and the results were compared with the three major world population data [Yoruba of Ibadan, Nigeria (YRI), Utah residents with northern and Western Europe ancestry (CEU) and Han Chinese of Beijing, China (CHB)] available in the HapMap database. The Aché clearly differentiated from the other Amerindians, but when all Native Americans were compared with the samples of other ethnic groups the lowest difference (0.08) was found with CHB (Asians), the second lowest (0.15) with YRI (Africans) and the most marked with CEU (European-derived). The considerable intra and interethnic differences found can be explained both in terms of diverse evolutionary distances and more recent environmental pathogen exposures; and they should be appropriately considered prior to any specific public health action.

Association of a carboxylesterase 1 polymorphism with appetite reduction in children and adolescents with attention-deficit/hyperactivity disorder treated with methylphenidate.

Carboxylesterase 1 is the enzyme involved in methylphenidate (MPH) metabolism. The aim of this study was to evaluate the association between a -75 T>G polymorphism and appetite reduction in children with attention-deficit/hyperactivity disorder (ADHD). A sample of 213 children with ADHD was investigated. The primary outcome was appetite reduction measured by the Barkley Stimulant Side Effect Rating Scale applied at baseline, at 1 and 3 months of treatment. MPH doses were augmented until no further clinical improvement or significant adverse events occurred. The G allele presented a trend for association with appetite reduction scores (P=0.05). A significant interaction between the G allele and treatment over time for appetite reduction scores was also observed (P=0.03). The G allele carriers presented a higher risk for appetite reduction worsening when compared with T allele homozygotes (odds ratio=3.47, P=0.01). The present results suggest an influence of carboxylesterase 1 -75 T>G polymorphism on the worsening of appetite reduction with MPH treatment in youths with ADHD.

Is there a role for rare variants in DRD4 gene in the susceptibility for ADHD? Searching for an effect of allelic heterogeneity.

Although several studies have demonstrated an association between the 7-repeat (7R) allele in the 48-bp variable number of tandem repeats (VNTRs) in the exon 3 at dopamine receptor D4 (DRD4) gene and attention-deficit/hyperactivity disorder (ADHD), others failed to replicate this finding. In this study, a total of 786 individuals with ADHD were genotyped for DRD4 exon 3 VNTR. All 7R homozygous subjects were selected for VNTR re-sequencing. Subjects homozygous for the 4R allele were selected paired by age, ancestry and disorder subtypes in order to have a sample as homogeneous as possible with 7R/7R individuals. Using these criteria, 103 individuals (66 with ADHD and 37 control individuals) were further investigated. An excess of rare variants were observed in the 7R alleles of ADHD patient when compared with controls (P=0.031). This difference was not observed in 4R allele. Furthermore, nucleotide changes that predict synonymous and non-synonymous substitutions were more common in the 7R sample (P=0.008 for total substitutions and P=0.043 for non-synonymous substitutions). In silico prediction of structural/functional alterations caused by these variants have also been observed. Our findings suggest that not only repeat length but also DNA sequence should be assessed to better understand the role of DRD4 exon 3 VNTR in ADHD genetic susceptibility.

The influence of the S19W SNP of the APOA5 gene on triglyceride levels in southern Brazil: interactions with the APOE gene, sex and menopause status.

BACKGROUND AND AIMS: Hypertriglyceridemia is an important independent risk factor for coronary artery diseases and is determined by a wide range of factors, both genetic and exogenous. The A5 apolipoprotein, which is associated with the synthesis and removal of triglycerides (TG), is encoded by the APOA5 gene. One of the polymorphisms of this gene that has been the focus of a large number of studies, and which appears to be associated with increased TG, is S19W (rs 3135506). In this study, we examined the influence of this single nucleotide polymorphism (SNP) on TG levels of a sample of southern Brazilians. METHODS AND RESULTS: Samples obtained from 567 people of European descent were genotyped; interactions between this variant and anthropometric variables were analyzed, and the effects of lifestyle, sex, menopause, and variations of the APOE gene were evaluated. We found that the 19W allele is associated with increased TG (p = 0.025) and that this influence was modulated by sex (p = 0.003), menopause (p = 0.022) and the presence of the E*4 allele (p = 0.027). CONCLUSION: Our data showed, for the first time, the importance and magnitude of the influence of the S19W variant in a southern Brazilian population.

Investigation of genetic susceptibility to Mycobacterium tuberculosis (VDR and IL10 genes) in a population with a high level of substructure in the Brazilian Amazon region.

OBJECTIVES: Tuberculosis (TB) is an infectious and contagious disease that has been very influential in human history and presents high rates of mortality. The objective of this study was to investigate the association of VDR, IL10, and SLC11A1 gene polymorphisms with susceptibility to the presence of Mycobacterium tuberculosis infection. METHODS: A total of 135 patients with confirmed TB and 141 healthy individuals were included in the analysis. Blood samples were collected for DNA extraction. Genotyping of the polymorphisms in the VDR and IL10 genes was performed by real-time PCR, and genotyping of the polymorphisms in the SLC11A1 gene by conventional PCR, followed by visualization in polyacrylamide gel. The genomic ancestry was obtained using an autosomal panel with 48 insertion/deletion ancestry-informative markers. RESULTS: Polymorphisms TaqI (TT, p=0.004), FokI (CC and CC+CT, p=0.012 and p=0.003, respectively), and BsmI (GG, p=0.008) in the VDR gene, as well as A-592C (GC+AG, p=0.001) in the IL10 gene, were significantly associated with susceptibility to TB In addition, high production of VDR combined with low production of IL10 showed protection for the TB group (p=0.035). CONCLUSIONS: The VDR polymorphisms may confer an increased risk and the IL10 haplotype may be a protection factor for the presence of M. tuberculosis infection in the Brazilian population.

Association of slow N-acetyltransferase 2 profile and anti-TB drug-induced hepatotoxicity in patients from Southern Brazil.

PURPOSE: To determine the frequency of N-acetyltransferase 2 (NAT2) polymorphisms, the NAT2 acetylation profile and its relation to the incidence of gastrointestinal adverse drug reactions (ADRs), anti-tuberculosis (TB) drug-induced hepatotoxicity, and the clinical risk factors for hepatotoxicity in a population from Brazil. METHODS: Two hundred and fifty-four Brazilian TB patients using isoniazid (INH), rifampicin (RMP), and pirazinamide (PZA) were tested in a prospective cohort study. NAT2 genotyping was performed by direct PCR sequencing. The association between gastrointestinal ADRs/hepatotoxicity and the NAT2 profile genotype was evaluated by univariate analysis and multiple logistic regression. RESULTS: Of the 254 patients analyzed, 69 (27.2%) were slow acetylators and 185 (72.8%) were fast acetylators. Sixty-five (25.6%) patients were human immunodeficiency virus (HIV)-positive. Thirty-three (13%) and 14 (5.5%) patients developed gastrointestinal ADR and hepatotoxicity, respectively. Of the 14 hepatotoxicity patients, nine (64.3%) were slow acetylators and five (35.7%) were fast acetylators. Sex, age, presence of hepatitis C virus, alcohol abuse, and baseline aminotransferases were not found to be risk factors for hepatotoxicity. However, logistic regression analysis revealed that slow acetylator status and the presence of HIV (p < 0.05) were independent risk factors for hepatotoxicity. CONCLUSIONS: Our findings show that HIV-positive patients that have the slow acetylation profile are significantly associated with a higher risk of developing hepatotoxicity due to anti-TB drugs.

Effects of a PPARG gene variant on obesity characteristics in Brazil.

The contribution of genetic factors to the development of obesity has been widely recognized, but the identity of the genes involved has not yet been fully clarified. Variation in genes involved in adipocyte differentiation and energy metabolism is expected to have a role in the etiology of obesity. We assessed the potential association of a polymorphism in one candidate gene, peroxisome proliferator-activated receptor-gamma (PPARGgamma), involved in these pathways and obesity-related phenotypes in 335 Brazilians of European descent. All individuals included in the sample were adults. Pregnant women, as well as those individuals with secondary hyperlipidemia due to renal, liver or thyroid disease, and diabetes, were not invited to participate in the study; all other individuals were included. The gene variant PPARG Pro12Ala was studied by a PCR-based method and the association between this genetic polymorphism and obesity-related phenotypes was evaluated by analysis of covariance. Variant allele frequency was PPARG Ala12 = 0.09 which is in the same range as described for European and European-derived populations. No statistically significant differences were observed for mean total cholesterol, LDL cholesterol, HDL cholesterol, or triglyceride levels among PPARG genotypes in either gender. In the male sample, an association between the PPARG Pro12Ala variant and body mass index was detected, with male carriers of the Ala variant presenting a higher mean body mass index than wild-type homozygotes (28.3 vs 26.2 kg/m2, P = 0.037). No effect of this polymorphism was detected in women. This finding suggests that the PPARG gene has a gender-specific effect and contributes to the susceptibility to obesity in this population.

Estrogen receptor 1 gene polymorphisms and coronary artery disease in the Brazilian population.

We examined the association of three established single nucleotide polymorphisms, IVS1-397T>C, IVS1-351A>G, and +261G>C, in the ESR1 gene with the prevalence and severity of coronary atherosclerosis in a southern Brazilian population of European ancestry. Three hundred and forty-one subjects (127 women and 214 men) with coronary artery disease (CAD) were classified as having significant disease (CAD+ patient group) when they showed 60% or more luminal stenosis in at least one coronary artery or major branch segment at angiography; patients with 10% or less luminal stenosis were considered to have minimal CAD (CAD- patient group). The control sample consisted of 142 subjects (79 women and 63 men) without significant disease, in whom coronary angiography to rule out the presence of asymptomatic CAD was not performed. The polymorphisms were investigated by polymerase chain reaction followed by restriction analyses. In the male sample, the +261G>C*C allele was more frequent in CAD+ than CAD- subjects (8 versus 1%, P = 0.024). Homozygosity for the C allele of the IVS1-397T>C polymorphism was also significantly associated with increased CAD severity (OR: 2.99; 95% CI = 1.35-6.63; P = 0.007). In agreement with previous findings, these results suggest that the IVS1-397T>C*C allele was associated with CAD severity independent of gender, whereas the association of the +261G>C variant with CAD was observed in males only. The relation between ESR1 variation and CAD may influence clinical decisions such as the use of hormone therapy, and additionally will be helpful to identify the genetic susceptibility determinants of cardiovascular disease development.

APOA1/C3/A4 gene cluster variability and lipid levels in Brazilian children.

Genetic studies have suggested that polymorphisms of genes coding for apolipoproteins are significant determinants of serum lipoprotein and lipid levels in adults. However, only a few studies have investigated the association of these polymorphisms in children. Therefore, in the present investigation we studied the distribution of APOA1 -75 G>A, +83 C>T, APOC3 -482 C>T, -455 T>C and 3238 C>G, and APOA4 Q360H and T347S polymorphisms and their influence on plasma lipoprotein levels in children from a Brazilian northeastern admixed population. The seven polymorphic sites were genotyped in 414 children aged 5 to 15 years (mean 8.9 +/- 2.9). The genotypes of the seven polymorphic sites were assessed by PCR-RFLP methods. The frequencies of the less common alleles were, in general, intermediate among parental populations, as expected. Strong linkage disequilibrium was detected between polymorphisms at the APOA1, APOC3 and APOA4 loci in this admixed population sample. Overall the genotype effects seen in adults were weaker or absent in children. The APOC3/-455 and APOA4 T347S variants showed significant effects on HDL cholesterol in girls (P = 0.033 and P = 0.016, respectively). Significantly higher plasma total (P = 0.003) and LDL cholesterol (P = 0.004) levels were observed in boys who were carriers of the 3238G allele at the APOC3/3238 C>G site. These results disclosed an overall absence of associations between these polymorphisms and lipids in children. This finding is not unexpected because expression of the effect of these polymorphisms might depend on the interaction with environmental variables both internal and external to the individual.

LPHN3 and attention-deficit/hyperactivity disorder: a susceptibility and pharmacogenetic study.

Latrophilin 3 (LPHN3) is a brain-specific member of the G-protein coupled receptor family associated to both attention-deficit/hyperactivity disorder (ADHD) genetic susceptibility and methylphenidate (MPH) pharmacogenetics. Interactions of LPHN3 variants with variants harbored in the 11q chromosome improve the prediction of ADHD development and medication response. The aim of this study was to evaluate the role of LPHN3 variants in childhood ADHD susceptibility and treatment response in a naturalistic clinical cohort. The association between LPHN3 and ADHD was evaluated in 523 children and adolescents with ADHD and 132 controls. In the pharmacogenetic study, 172 children with ADHD were investigated. The primary outcome measure was the parent-rated Swanson, Nolan and Pelham Scale - version IV applied at baseline, first and third months of treatment with MPH. The results reported herein suggest the CGC haplotype derived from single nucleotide polymorphisms (SNPs) rs6813183, rs1355368 and rs734644 as an ADHD risk haplotype (P = 0.02, OR = 1.46). Although non-significant after multiple testing correction, its interaction with the 11q chromosome SNP rs965560 slightly increases risk (P = 0.03, OR = 1.55). Homozygous individuals for the CGC haplotype showed faster response to MPH treatment as a significant interaction effect between CGC haplotype and treatment over time was observed (P < 0.001). Homozygous individuals for the GT haplotype derived from SNPs rs6551665 and rs1947275 showed a nominally significant interaction with treatment over time (P = 0.04). Our findings replicate previous findings reporting that LPHN3 confers ADHD susceptibility, and moderates MPH treatment response in children and adolescents with ADHD.

Genetic variation among the Mapuche Indians from the Patagonian region of Argentina: mitochondrial DNA sequence variation and allele frequencies of several nuclear genes.

DNA samples from 60 Mapuche Indians, representing 39 maternal lineages, were genetically characterized for (1) nucleotide sequences of the mtDNA control region; (2) presence or absence of a nine base duplication in mtDNA region V; (3) HLA loci DRB1 and DQA1; (4) variation at three nuclear genes with short tandem repeats; and (5) variation at the polymorphic marker D2S44. The genetic profile of the Mapuche population was compared to other Amerinds and to worldwide populations. Two highly polymorphic portions of the mtDNA control region, comprising 650 nucleotides, were amplified by the polymerase chain reaction (PCR) and directly sequenced. The 39 maternal lineages were defined by two or three generation families identified by the Mapuches. These 39 lineages included 19 different mtDNA sequences that could be grouped into four classes. The same classes of sequences appear in other Amerinds from North, Central, and South American populations separated by thousands of miles, suggesting that the origin of the mtDNA patterns predates the migration to the Americas. The mtDNA sequence similarity between Amerind populations suggests that the migration throughout the Americas occurred rapidly relative to the mtDNA mutation rate. HLA DRB1 alleles 1602 and 1402 were frequent among the Mapuches. These alleles also occur at high frequency among other Amerinds in North and South America, but not among Spanish, Chinese or African-American populations. The high frequency of these alleles throughout the Americas, and their specificity to the Americas, supports the hypothesis that Mapuches and other Amerind groups are closely related.(ABSTRACT TRUNCATED AT 250 WORDS)

The TaqI A1 allele of the dopamine D2 receptor gene and alcoholism in Brazil: association and interaction with stress and harm avoidance on severity prediction.

Allele and genotype frequencies of the TaqI A polymorphism of dopamine D2 receptor (DRD2) gene were compared in 115 alcohol-dependent Brazilian males and 114 ethnically matched controls. Regression analyses were performed to test for an interactive effect between the DRD2 TaqI A1 allele and measures of stress and harm avoidance on severity of alcoholism and number of antisocial personality symptoms. A slightly positive association of DRD2 TaqI A1 genotypes with alcoholism was observed, by standard and molecular heterosis approaches. The DRD2 TaqI A1 allele showed significant interaction with stress and harm avoidance in predicting the severity of physiologic dependence, and with harm avoidance for the number of antisocial personality symptoms. Separate partial correlation analyses showed that stress-related variables were significantly correlated with severity scores in alcoholics with the allele, but not in those without it. This is the first demonstration of an interaction between a genetic polymorphism and stress-related measures on the severity of psychiatric disorders.

Hb F levels, longevity of homozygotes and clinical course of sickle cell anemia in Brazil.

A sample of 354 individuals with sickle cell anemia ascertained in the city of Rio de Janeiro was studied to investigate the relationships between Hb F level, morbidity, and mortality. The mean Hb F level was 6.41 +/- 5.21%. The relationship between age and the proportion of Hb F can be described as a quadratic polynomial distribution, the level falling from approximately 11% in the first year to 4% at 25 years and then rising proportionally after 30 years. The correlations between Hb F level and 140 variables, including hematological values, signs and symptoms of the disease, as well as therapeutic requirements, showed that the patients with high Hb F levels are less anemic and have a more benign course. Several significant correlations (between amount of Hb F and the following clinical signs: pallor of mucous membranes, jaundice, cholelithiasis, leg ulcers, bronchial asthma, increased pulmonary vascularity, left ventricular hypertrophy, and osteomyelitis) are being reported here for the first time.

Attention-deficit hyperactivity disorder: a study of association with both the dopamine transporter gene and the dopamine D4 receptor gene.

Attention-deficit hyperactivity disorder (ADHD) is one of the most common psychiatric disorders of childhood. The role of genetic factors in its etiology is strongly supported by family, adoption, and twin studies. Several investigations have reported associations between ADHD and both the 7-repeat allele of the 48 bp VNTR at the DRD4 gene and the 10-repeat allele of the 40 bp VNTR at the DAT1 gene, but the results have been inconsistent. A sample of 81 Brazilian ADHD children and adolescents and their parents were screened for these DRD4 and DAT1 VNTRs. An excess of the DRD4 7-repeat allele was observed when both ADHD probands and their parents were compared with an ethnically matched control sample (chi-square = 11.55, P = 0.03; chi-square = 12.17, P = 0.03, respectively). However, haplotype relative risk (HRR) analysis showed no preferential transmission of the DRD4 7-repeat allele. No evidence of association with the DAT1 polymorphism was detected by both approaches. Nevertheless, an interaction effect of both genes on ADHD hyperactive/impulsive dimension was observed (F = 4.68; P = 0.03). These results add to the group of studies that together suggest a small effect of these genes in the susceptibility to ADHD.