RESUMO
Interest in the cerebellum is expanding given evidence of its contributions to cognition and emotion, and dysfunction in various psychopathologies. However, research into its genetic architecture and shared influences with liability for mental disorders is lacking. We conducted a genome-wide association study (GWAS) of total cerebellar volume and underlying cerebellar lobe volumes in 33,265 UK-Biobank participants. Total cerebellar volume was heritable (h2SNP = 50.6%), showing moderate genetic homogeneity across lobes (h2SNP from 35.4% to 57.1%; mean genetic correlation between lobes rg ≈ 0.44). We identified 33 GWAS signals associated with total cerebellar volume, of which 6 are known to alter protein-coding gene structure, while a further five mapped to genomic regions known to alter cerebellar tissue gene expression. Use of summary data-based Mendelian randomisation further prioritised genes whose change in expression appears to mediate the SNP-trait association. In total, we highlight 21 unique genes of greatest interest for follow-up analyses. Using LD-regression, we report significant genetic correlations between total cerebellar volume and brainstem, pallidum and thalamus volumes. While the same approach did not result in significant correlations with psychiatric phenotypes, we report enrichment of schizophrenia, bipolar disorder and autism spectrum disorder associated signals within total cerebellar GWAS results via conditional and conjunctional-FDR analysis. Via these methods and GWAS catalogue, we identify which of our cerebellar genomic regions also associate with psychiatric traits. Our results provide important insights into the common allele architecture of cerebellar volume and its overlap with other brain volumes and psychiatric phenotypes.
Assuntos
Transtorno do Espectro Autista , Transtornos Mentais , Bancos de Espécimes Biológicos , Cerebelo , Predisposição Genética para Doença/genética , Estudo de Associação Genômica Ampla , Humanos , Transtornos Mentais/genética , Polimorfismo de Nucleotídeo Único/genética , Reino UnidoRESUMO
Genetic studies have revealed the involvement of hundreds of gene variants in autism. Their risk effects are highly variable, and they are frequently related to other conditions besides autism. However, many different variants converge on common biological pathways. These findings indicate that aetiological heterogeneity, variable penetrance and genetic pleiotropy are pervasive characteristics of autism genetics. Although this advancing insight should improve clinical care, at present there is a substantial discrepancy between research knowledge and its clinical application. In this Review, we discuss the current challenges and opportunities for the translation of autism genetics knowledge into clinical practice.
Assuntos
Transtorno Autístico/genética , Transtorno Autístico/fisiopatologia , Transtorno Autístico/terapia , Predisposição Genética para Doença , Técnicas de Genotipagem , HumanosRESUMO
Autism spectrum disorders (ASD) are heterogeneous disorders with a high heritability and complex genetic architecture. Due to the central role of the fragile X mental retardation gene 1 protein (FMRP) pathway in ASD we investigated common functional variants of ASD risk genes regulating FMRP. We genotyped ten SNPs in two German patient sets (N = 192 and N = 254 families, respectively) and report association for rs7170637 (CYFIP1; set 1 and combined sets), rs6923492 (GRM1; combined sets), and rs25925 (CAMK4; combined sets). An additional risk score based on variants with an odds ratio (OR) >1.25 in set 1 and weighted by their respective log transmitted/untransmitted ratio revealed a significant effect (OR 1.30, 95 % CI 1.11-1.53; P = 0.0013) in the combined German sample. A subsequent meta-analysis including the two German samples, the "Strict/European" ASD subsample of the Autism Genome Project (1,466 families) and a French case/control (541/366) cohort showed again association of rs7170637-A (OR 0.85, 95 % CI 0.75-0.96; P = 0.007) and rs25925-G (OR 1.31, 95 % CI 1.04-1.64; P = 0.021) with ASD. Functional analyses revealed that these minor alleles predicted to alter splicing factor binding sites significantly increase levels of an alternative mRNA isoform of the respective gene while keeping the overall expression of the gene constant. These findings underpin the role of ASD candidate genes in postsynaptic FMRP regulation suggesting that an imbalance of specific isoforms of CYFIP1, an FMRP interaction partner, and CAMK4, a transcriptional regulator of the FMRP gene, modulates ASD risk. Both gene products are related to neuronal regulation of synaptic plasticity, a pathomechanism underlying ASD and may thus present future targets for pharmacological therapies in ASD.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/genética , Proteína Quinase Tipo 4 Dependente de Cálcio-Calmodulina/genética , Transtornos Globais do Desenvolvimento Infantil/genética , Proteína do X Frágil da Deficiência Intelectual/genética , Predisposição Genética para Doença , Polimorfismo de Nucleotídeo Único , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Adolescente , Alelos , Proteína Quinase Tipo 4 Dependente de Cálcio-Calmodulina/metabolismo , Criança , Transtornos Globais do Desenvolvimento Infantil/etnologia , Transtornos Globais do Desenvolvimento Infantil/metabolismo , Transtornos Globais do Desenvolvimento Infantil/patologia , Pré-Escolar , Feminino , Proteína do X Frágil da Deficiência Intelectual/metabolismo , Regulação da Expressão Gênica , Técnicas de Genotipagem , Humanos , Masculino , Plasticidade Neuronal/genética , Ligação Proteica , Fatores de Risco , Transdução de Sinais , População BrancaRESUMO
Large numbers of control individuals with genome-wide genotype data are now available through various databases. These controls are regularly used in case-control genome-wide association studies (GWAS) to increase the statistical power. Controls are often "unselected" for the disease of interest and are not matched to cases in terms of confounding factors, making the studies more vulnerable to confounding as a result of population stratification. In this communication, we demonstrate that family-based designs can integrate unselected controls from other studies into the analysis without compromising the robustness of family-based designs against genetic confounding. The result is a hybrid case-control family-based analysis that achieves higher power levels than population-based studies with the same number of cases and controls. This strategy is widely applicable and works ideally for all situations in which both family and case-control data are available. The approach consists of three steps. First, we perform a standard family-based association test that does not utilize the between-family component. Second, we use the between-family information in conjunction with the genotypes from unselected controls in a Cochran-Armitage trend test. The p values from this step are then calculated by rank ordering the individual Cochran-Armitage trend test statistics for the genotype markers. Third, we generate a combined p value with the association p values from the first two steps. Simulation studies are used to assess the achievable power levels of this method compared to standard analysis approaches. We illustrate the approach by an application to a GWAS of attention deficit hyperactivity disorder parent-offspring trios and publicly available controls.
Assuntos
Simulação por Computador , Estudo de Associação Genômica Ampla , Modelos Teóricos , Estudos de Casos e Controles , Genótipo , Humanos , Fenótipo , Projetos de PesquisaRESUMO
The similarity between aspects of the clinical presentation of schizophrenia and autism spectrum disorders (ASD) suggests that elements of the biological etiology may also be shared between these two disorders. Recently, an increasing number of rare, mostly structural genetic variants are reported to increase the risk of both schizophrenia and ASD. We hypothesized that given this evidence for a shared genetic background based on rare genetic variants, common risk alleles may also be shared between ASD and schizophrenia. To test this hypothesis, the polygenic score, which summarizes the collective effect of a large number of common risk alleles, was used. We examined whether the polygenic score derived from a schizophrenia case-control dataset, previously reported by Purcell et al., was able to differentiate ASD cases from controls. The results demonstrate that the schizophrenia-derived polygenic score is not different between ASD cases and controls, indicating that there is no important sharing of common risk alleles between the two neuropsychiatric disorders. Possibly, common risk alleles are less important in ASD in comparison to their more prominent role in schizophrenia and bipolar disorders. These findings provide important novel insights into shared and distinct elements of the genetic architecture of autism and schizophrenia.
Assuntos
Transtorno Autístico/genética , Predisposição Genética para Doença , Variação Genética , Esquizofrenia/genética , Estudos de Casos e Controles , Marcadores Genéticos , Humanos , Herança Multifatorial/genética , Fatores de RiscoRESUMO
BACKGROUND: Attention-deficit/hyperactivity disorder (ADHD) is highly heritable, but little is known about the relative effects of transmitted (i.e., direct) and nontransmitted (i.e., indirect) common variant risks. Using parent-offspring trios, we tested whether polygenic liability for neurodevelopmental and psychiatric disorders and lower cognitive ability is overtransmitted to ADHD probands. We also tested for indirect or genetic nurture effects by examining whether nontransmitted ADHD polygenic liability is elevated. Finally, we examined whether complete trios are representative of the clinical ADHD population. METHODS: Polygenic risk scores (PRSs) for ADHD, anxiety, autism, bipolar disorder, depression, obsessive-compulsive disorder, schizophrenia, Tourette syndrome, and cognitive ability were calculated in UK control subjects (n = 5081), UK probands with ADHD (n = 857), their biological parents (n = 328 trios), and also a replication sample of 844 ADHD trios. RESULTS: ADHD PRSs were overtransmitted and cognitive ability and obsessive-compulsive disorder PRSs were undertransmitted. These results were independently replicated. Overtransmission of polygenic liability was not observed for other disorders. Nontransmitted alleles were not enriched for ADHD liability compared with control subjects. Probands from incomplete trios had more hyperactive-impulsive and conduct disorder symptoms, lower IQ, and lower socioeconomic status than complete trios. PRS did not vary by trio status. CONCLUSIONS: The results support direct transmission of polygenic liability for ADHD and cognitive ability from parents to offspring, but not for other neurodevelopmental/psychiatric disorders. They also suggest that nontransmitted neurodevelopmental/psychiatric parental alleles do not contribute indirectly to ADHD via genetic nurture. Furthermore, ascertainment of complete ADHD trios may be nonrandom, in terms of demographic and clinical factors.
Assuntos
Transtorno do Deficit de Atenção com Hiperatividade , Transtorno da Conduta , Síndrome de Tourette , Humanos , Transtorno do Deficit de Atenção com Hiperatividade/epidemiologia , Herança Multifatorial/genética , Síndrome de Tourette/genética , Transtorno da Conduta/psicologia , PaisRESUMO
While over 100 genes have been associated with autism, little is known about the prevalence of variants affecting them in individuals without a diagnosis of autism. Nor do we fully appreciate the phenotypic diversity beyond the formal autism diagnosis. Based on data from more than 13,000 individuals with autism and 210,000 undiagnosed individuals, we estimated the odds ratios for autism associated to rare loss-of-function (LoF) variants in 185 genes associated with autism, alongside 2,492 genes displaying intolerance to LoF variants. In contrast to autism-centric approaches, we investigated the correlates of these variants in individuals without a diagnosis of autism. We show that these variants are associated with a small but significant decrease in fluid intelligence, qualification level and income and an increase in metrics related to material deprivation. These effects were larger for autism-associated genes than in other LoF-intolerant genes. Using brain imaging data from 21,040 individuals from the UK Biobank, we could not detect significant differences in the overall brain anatomy between LoF carriers and non-carriers. Our results highlight the importance of studying the effect of the genetic variants beyond categorical diagnosis and the need for more research to understand the association between these variants and sociodemographic factors, to best support individuals carrying these variants.
Assuntos
Transtorno do Espectro Autista , Transtorno Autístico , Humanos , Transtorno Autístico/genética , Fenótipo , Heterozigoto , EncéfaloRESUMO
OBJECTIVE: Postpartum depression (PPD) is a common subtype of major depressive disorder (MDD) that is more heritable, yet is understudied in psychiatric genetics. The authors conducted meta-analyses of genome-wide association studies (GWASs) to investigate the genetic architecture of PPD. METHOD: Meta-analyses were conducted on 18 cohorts of European ancestry (17,339 PPD cases and 53,426 controls), one cohort of East Asian ancestry (975 cases and 3,780 controls), and one cohort of African ancestry (456 cases and 1,255 controls), totaling 18,770 PPD cases and 58,461 controls. Post-GWAS analyses included 1) single-nucleotide polymorphism (SNP)-based heritability ([Formula: see text]), 2) genetic correlations between PPD and other phenotypes, and 3) enrichment of the PPD GWAS findings in 27 human tissues and 265 cell types from the mouse central and peripheral nervous system. RESULTS: No SNP achieved genome-wide significance in the European or the trans-ancestry meta-analyses. The [Formula: see text] of PPD was 0.14 (SE=0.02). Significant genetic correlations were estimated for PPD with MDD, bipolar disorder, anxiety disorders, posttraumatic stress disorder, insomnia, age at menarche, and polycystic ovary syndrome. Cell-type enrichment analyses implicate inhibitory neurons in the thalamus and cholinergic neurons within septal nuclei of the hypothalamus, a pattern that differs from MDD. CONCLUSIONS: While more samples are needed to reach genome-wide levels of significance, the results presented confirm PPD as a polygenic and heritable phenotype. There is also evidence that despite a high correlation with MDD, PPD may have unique genetic components. Cell enrichment results suggest GABAergic neurons, which converge on a common mechanism with the only medication approved by the U.S. Food and Drug Administration for PPD (brexanolone).
Assuntos
Transtorno Bipolar , Depressão Pós-Parto , Transtorno Depressivo Maior , Feminino , Humanos , Animais , Camundongos , Transtorno Depressivo Maior/genética , Estudo de Associação Genômica Ampla , Depressão Pós-Parto/genética , Predisposição Genética para Doença , Transtorno Bipolar/genética , Polimorfismo de Nucleotídeo Único/genéticaRESUMO
Attention deficit/hyperactivity disorder (ADHD) demonstrates a high level of comorbidity with major depressive disorder (MDD). One possible contributor to this is that the two disorders show high genetic correlation. However, the specific regions of the genome that may be responsible for this overlap are unclear. To identify variants associated with both ADHD and MDD, we performed a meta-analysis of GWAS of ADHD and MDD. All genome wide significant (p < 5 × 10-8) SNPs in the meta-analysis that were also strongly associated (p < 5 × 10-4) independently with each disorder were followed up. These putatively pleiotropic SNPs were tested for additional associations across a broad range of phenotypes. Fourteen linkage disequilibrium-independent SNPs were associated with each disorder separately (p < 5 × 10-4) and in the cross-disorder meta-analysis (p < 5 × 10-8). Nine of these SNPs had not been highlighted previously in either individual GWAS. Evidence supported nine of the fourteen SNPs acting as eQTL and two as brain eQTL. Index SNPs and their genomic regions demonstrated associations with other mental health phenotypes. Through conducting meta-analysis on ADHD and MDD only, our results build upon the previously observed genetic correlation between ADHD and MDD and reveal novel genomic regions that may be implicated in this overlap.
Assuntos
Transtorno do Deficit de Atenção com Hiperatividade/genética , Transtorno Depressivo Maior/genética , Predisposição Genética para Doença , Variação Genética , Estudo de Associação Genômica Ampla , Polimorfismo de Nucleotídeo Único , Algoritmos , Alelos , Genômica , Humanos , Desequilíbrio de Ligação , Fenótipo , Locos de Características QuantitativasRESUMO
OBJECTIVE: Certain copy number variants (CNVs) greatly increase the risk of autism. The authors conducted a genetics-first study to investigate whether heterogeneity in the clinical presentation of autism is underpinned by specific genotype-phenotype relationships. METHODS: This international study included 547 individuals (mean age, 12.3 years [SD=4.2], 54% male) who were ascertained on the basis of having a genetic diagnosis of a rare CNV associated with high risk of autism (82 16p11.2 deletion carriers, 50 16p11.2 duplication carriers, 370 22q11.2 deletion carriers, and 45 22q11.2 duplication carriers), as well as 2,027 individuals (mean age, 9.1 years [SD=4.9], 86% male) with autism of heterogeneous etiology. Assessments included the Autism Diagnostic Interview-Revised and IQ testing. RESULTS: The four genetic variant groups differed in autism symptom severity, autism subdomain profile, and IQ profile. However, substantial variability was observed in phenotypic outcome in individual genetic variant groups (74%-97% of the variance, depending on the trait), whereas variability between groups was low (1%-21%, depending on the trait). CNV carriers who met autism criteria were compared with individuals with heterogeneous autism, and a range of profile differences were identified. When clinical cutoff scores were applied, 54% of individuals with one of the four CNVs who did not meet full autism diagnostic criteria had elevated levels of autistic traits. CONCLUSIONS: Many CNV carriers do not meet full diagnostic criteria for autism but nevertheless meet clinical cutoffs for autistic traits. Although profile differences between variants were observed, there is considerable variability in clinical symptoms in the same variant.
Assuntos
Transtorno Autístico/genética , Variações do Número de Cópias de DNA/genética , Predisposição Genética para Doença/genética , Transtorno Autístico/diagnóstico , Transtorno Autístico/epidemiologia , Criança , Deleção de Genes , Estudos de Associação Genética , Heterozigoto , Humanos , Entrevista Psicológica , Masculino , Prevalência , Fatores de Risco , Índice de Gravidade de DoençaRESUMO
Research has shown differences in subcortical brain volumes between participants with schizophrenia and healthy controls. However, none of these differences have been found to associate with schizophrenia polygenic risk. Here, in a large sample (n = 14,701) of unaffected participants from the UK Biobank, we test whether schizophrenia polygenic risk scores (PRS) limited to specific gene-sets predict subcortical brain volumes. We compare associations with schizophrenia PRS at the whole genome level ('genomic', including all SNPs associated with the disorder at a p-value threshold < 0.05) with 'genic' PRS (based on SNPs in the vicinity of known genes), 'intergenic' PRS (based on the remaining SNPs), and genic PRS limited to SNPs within 7 gene-sets previously found to be enriched for genetic association with schizophrenia ('abnormal behaviour,' 'abnormal long-term potentiation,' 'abnormal nervous system electrophysiology,' 'FMRP targets,' '5HT2C channels,' 'CaV2 channels' and 'loss-of-function intolerant genes'). We observe a negative association between the 'abnormal behaviour' gene-set PRS and volume of the right thalamus that survived correction for multiple testing (ß = -0.031, pFDR = 0.005) and was robust to different schizophrenia PRS p-value thresholds. In contrast, the only association with genomic PRS surviving correction for multiple testing was for right pallidum, which was observed using a schizophrenia PRS p-value threshold < 0.01 (ß = -0.032, p = 0.0003, pFDR = 0.02), but not when using other PRS P-value thresholds. We conclude that schizophrenia PRS limited to functional gene sets may provide a better means of capturing differences in subcortical brain volume than whole genome PRS approaches.
Assuntos
Esquizofrenia , Bancos de Espécimes Biológicos , Encéfalo/diagnóstico por imagem , Predisposição Genética para Doença , Estudo de Associação Genômica Ampla , Humanos , Herança Multifatorial , Esquizofrenia/genética , Reino UnidoRESUMO
It is hypothesised that autism symptoms are present in Attention-Deficit/Hyperactivity Disorder (ADHD), are familial and index subtypes of ADHD. Autism symptoms were compared in 821 ADHD probands, 1050 siblings and 149 controls. Shared familiality of autism symptoms and ADHD was calculated using DeFries-Fulker analysis. Autism symptoms were higher in probands than siblings or controls, and higher in male siblings than male controls. Autism symptoms were familial, partly shared with familiality of ADHD in males. Latent class analysis using SCQ-score yielded five classes; Class 1(31%) had few autism symptoms and low comorbidity; Classes 2-4 were intermediate; Class 5(7%) had high autism symptoms and comorbidity. Thus autism symptoms in ADHD represent a familial trait associated with increased neurodevelopmental and oppositional/conduct disorders.
Assuntos
Transtorno do Deficit de Atenção com Hiperatividade/epidemiologia , Transtorno Autístico/epidemiologia , Atividade Motora , Irmãos , Transtorno do Deficit de Atenção com Hiperatividade/classificação , Transtorno do Deficit de Atenção com Hiperatividade/diagnóstico , Transtorno do Deficit de Atenção com Hiperatividade/fisiopatologia , Transtorno Autístico/diagnóstico , Transtorno Autístico/fisiopatologia , Criança , Pré-Escolar , Comorbidade , Transtorno da Conduta/epidemiologia , Medo/psicologia , Feminino , Humanos , Transtornos do Desenvolvimento da Linguagem/epidemiologia , Masculino , Fenótipo , Escalas de Graduação Psiquiátrica/estatística & dados numéricos , Psicometria/métodos , Índice de Gravidade de Doença , Distribuição por Sexo , Irmãos/psicologia , Inquéritos e QuestionáriosRESUMO
Autism (OMIM %209850) is a neurodevelopmental disorder with a strong genetic component. We previously reported a de novo rearrangement of chromosome 2q31 in a patient with autism [Gallagher et al. (2003); J Autism Dev Disord 33(1):105-108]. Further cytogenetic analysis revealed this to be a 46,XY, t(9;2)(q31.1;q32.2q31.3) translocation. Association mapping with microsatellite and SNP markers of this translocated region on 2q revealed association with markers in Integrin alpha-4 (ITGA4; GeneID 3676). ITGA4 was tested for association in a sample of 179 trio-based families. SNP markers in exons 16 and 17 showed evidence of association. Mutation screening revealed a G to A synonymous variation in the last nucleotide of exon 16 (rs12690517), significantly associated with autism in the Irish sample (OR = 1.6; P = 0.04). The location of this SNP at a putative splice donor site may affect the splicing of the ITGA4 protein. Haplotype analysis showed significant overtransmission of haplotypes surrounding this marker. These markers were investigated in two additional samples, 102 families from Vanderbilt University (VT) (n = 102), and AGRE (n = 267). A non-significant trend towards overtransmission of the associated allele of rs12690517 in the Irish sample (OR = 1.2; P = 0.067) and haplotypes at the 3' end of ITGA4 was observed in the AGRE sample. The VT sample showed association with markers and haplotypes across the gene, but no association with the rs12690517 marker or its surrounding haplotypes. The combined sample showed evidence of association with rs12690517 (OR = 1.3; P = 0.008) and surrounding haplotypes. The findings indicate some evidence for the role of ITGA4 as candidate gene for autism.
Assuntos
Transtorno Autístico/genética , Cromossomos Humanos Par 2/genética , Predisposição Genética para Doença , Integrina alfa4/genética , Alelos , Mapeamento Cromossômico , Feminino , Haplótipos/genética , Humanos , Cariotipagem , Masculino , Repetições de Microssatélites/genética , Mutação/genética , Linhagem , Polimorfismo de Nucleotídeo Único/genéticaRESUMO
The considerable data-handling requirements for genome wide association studies (GWAS) prohibit individual calling of genotypes and create a reliance on sophisticated "genotype-calling algorithms." Despite their obvious utility, the current genotyping platforms and calling-algorithms used are not without their limitations. Specifically, some genotypes are not called due to the ambiguity of the data. Any bias in the missing data could create spurious results. Using data from the Genetic Analysis Information Network (GAIN) we observed that missing genotypes are not randomly distributed throughout the homozygous and heterozygous groups. Using simulation, we examined whether the level and type of missingness observed might influence deviation from the null-hypothesis under common case-control and family-based statistical approaches. Under a case-control model, where missingness is present in a case group but not the controls, we observed bias giving rise to genome-wide significant type-I error for missingness as low as 3%. The family-based association simulations show close to nominal type-I error at 4% genotype missingness. These findings have important implications to study design, quality-control procedures and reporting of findings in GWAS.
Assuntos
Família , Genoma Humano , Estudo de Associação Genômica Ampla , Genótipo , Algoritmos , Alelos , Viés , Estudos de Casos e Controles , Distribuição de Qui-Quadrado , Criança , Análise por Conglomerados , Simulação por Computador , Dosagem de Genes , Marcadores Genéticos , Genética Populacional , Haplótipos , Heterozigoto , Homozigoto , Humanos , Desequilíbrio de Ligação , Análise de Sequência com Séries de Oligonucleotídeos , Pais , Polimorfismo de Nucleotídeo ÚnicoRESUMO
There are conflicting reports suggesting that the parental origin of transmitted risk alleles may play a role in the etiology of attention deficit/hyperactivity disorder (ADHD). A recent report by Hawi and colleagues observed a generalized paternal over-transmission of alleles associated with ADHD. This was not replicated in more recent studies. Using data from a large multicenter study we examined the overall and gene-specific parent of origin effect in 554 independent SNPs across 47 genes. Transmission disequilibrium and explicit parent of origin test were performed using PLINK. Overall parent of origin effect was tested by Chi-square. There was no overall parent of origin effect in the IMAGE sample (chi(1)(2) = 1.82, P = 0.117). Five markers in three genes, DDC, TPH2, and SLC6A2 showed nominal association (P < 0.01) with ADHD combined subtype when restricted to maternal or paternal transmission only. Following the initial report by Hawi and co-workers three studies, including this one, found no evidence to support an overall parent of origin effect for markers associated with ADHD. We cannot however, exclude gene-specific parent of origin effect in the etiology ADHD.
Assuntos
Transtorno do Deficit de Atenção com Hiperatividade/genética , Interpretação Estatística de Dados , Predisposição Genética para Doença , Pais , Alelos , Transtorno do Deficit de Atenção com Hiperatividade/etiologia , Distribuição de Qui-Quadrado , Família , Marcadores Genéticos , Humanos , Desequilíbrio de Ligação , Polimorfismo de Nucleotídeo Único , Fatores de RiscoRESUMO
Attention deficit hyperactivity disorder (ADHD) is a complex condition with environmental and genetic etiologies. Up to this point, research has identified genetic associations with candidate genes from known biological pathways. In order to identify novel ADHD susceptibility genes, 600,000 SNPs were genotyped in 958 ADHD proband-parent trios. After applying data cleaning procedures we examined 429,981 autosomal SNPs in 909 family trios. We generated six quantitative phenotypes from 18 ADHD symptoms to be used in genome-wide association analyses. With the PBAT screening algorithm, we identified 2 SNPs, rs6565113 and rs552655 that met the criteria for significance within a specified phenotype. These SNPs are located in intronic regions of genes CDH13 and GFOD1, respectively. CDH13 has been implicated previously in substance use disorders. We also evaluated the association of SNPs from a list of 37 ADHD candidate genes that was specified a priori. These findings, along with association P-values with a magnitude less than 10(-5), are discussed in this manuscript. Seventeen of these candidate genes had association P-values lower then 0.01: SLC6A1, SLC9A9, HES1, ADRB2, HTR1E, DDC, ADRA1A, DBH, DRD2, BDNF, TPH2, HTR2A, SLC6A2, PER1, CHRNA4, SNAP25, and COMT. Among the candidate genes, SLC9A9 had the strongest overall associations with 58 association test P-values lower than 0.01 and multiple association P-values at a magnitude of 10(-5) in this gene. In sum, these findings identify novel genetic associations at viable ADHD candidate genes and provide confirmatory evidence for associations at previous candidate genes. Replication of these results is necessary in order to confirm the proposed genetic variants for ADHD.
Assuntos
Transtorno do Deficit de Atenção com Hiperatividade/genética , Predisposição Genética para Doença , Estudo de Associação Genômica Ampla , Locos de Características Quantitativas , Algoritmos , Transtorno do Deficit de Atenção com Hiperatividade/diagnóstico , Caderinas/genética , Análise por Conglomerados , Feminino , Marcadores Genéticos , Genoma Humano , Genótipo , Haplótipos , Humanos , Íntrons , Masculino , Modelos Genéticos , Linhagem , Polimorfismo de Nucleotídeo Único , ProbabilidadeRESUMO
A time-to-onset analysis for family-based samples was performed on the genomewide association (GWAS) data for attention deficit hyperactivity disorder (ADHD) to determine if associations exist with the age at onset of ADHD. The initial dataset consisted of 958 parent-offspring trios that were genotyped on the Perlegen 600,000 SNP array. After data cleaning procedures, 429,981 autosomal SNPs and 930 parent-offspring trios were used found suitable for use and a family-based logrank analysis was performed using that age at first ADHD symptoms as the quantitative trait of interest. No SNP achieved genome-wide significance, and the lowest P-values had a magnitude of 10(-7). Several SNPs among a pre-specified list of candidate genes had nominal associations including SLC9A9, DRD1, ADRB2, SLC6A3, NFIL3, ADRB1, SYT1, HTR2A, ARRB2, and CHRNA4. Of these findings SLC9A9 stood out as a promising candidate, with nominally significant SNPs in six distinct regions of the gene.
Assuntos
Transtorno do Deficit de Atenção com Hiperatividade/genética , Estudo de Associação Genômica Ampla , Adolescente , Idade de Início , Transtorno do Deficit de Atenção com Hiperatividade/diagnóstico , Criança , Pré-Escolar , Feminino , Marcadores Genéticos , Predisposição Genética para Doença , Genoma Humano , Haplótipos , Humanos , Desequilíbrio de Ligação , Masculino , Linhagem , Polimorfismo de Nucleotídeo Único , Probabilidade , Locos de Características Quantitativas , Estudos Retrospectivos , Trocadores de Sódio-Hidrogênio/genéticaRESUMO
Attention-deficit/hyperactivity disorder (ADHD) is typically characterized by inattention, excessive motor activity, impulsivity, and distractibility. Individuals with ADHD have significant impairment in family and peer relations, academic functioning, and show high co-morbidity with a wide range of psychiatric disorders including oppositional defiant disorder (ODD), conduct disorder (CD), anxiety disorder, depression, substance abuse, and pervasive developmental disorder (PDD). Family studies suggest that ADHD + CD represents a specific subtype of the ADHD disorder with familial risk factors only partly overlapping with those of ADHD alone. We performed a hypothesis-free analysis of the GAIN-ADHD sample to identify markers and genes important in the development of conduct problems in a European cohort of individuals with ADHD. Using the Family-Based Association Test (FBAT) package we examined three measures of conduct problems in 1,043,963 autosomal markers. This study is part of a series of exploratory analyses to identify candidate genes that may be important in ADHD and ADHD-related traits, such as conduct problems. We did not find genome-wide statistical significance (P < 5 x 10(-7)) for any of the tested markers and the three conduct problem traits. Fifty-four markers reached strong GWA signals (P < 10(-5)). We discuss these findings in the context of putative candidate genes and the implications of these findings in the understanding of the etiology of ADHD + CD. We aimed to achieve insight into the genetic etiology of a trait using a hypothesis-free study design and were able to identify a number of biologically interesting markers and genes for follow-up studies.
Assuntos
Transtorno do Deficit de Atenção com Hiperatividade , Transtorno da Conduta , Genoma Humano , Estudo de Associação Genômica Ampla , Locos de Características Quantitativas/genética , Algoritmos , Transtorno da Personalidade Antissocial/genética , Transtorno da Personalidade Antissocial/psicologia , Transtorno do Deficit de Atenção com Hiperatividade/epidemiologia , Transtorno do Deficit de Atenção com Hiperatividade/genética , Transtorno do Deficit de Atenção com Hiperatividade/psicologia , Transtornos de Deficit da Atenção e do Comportamento Disruptivo/complicações , Transtornos de Deficit da Atenção e do Comportamento Disruptivo/genética , Criança , Transtornos do Comportamento Infantil/epidemiologia , Transtornos do Comportamento Infantil/genética , Transtornos do Comportamento Infantil/psicologia , Estudos de Coortes , Comorbidade , Transtorno da Conduta/epidemiologia , Transtorno da Conduta/genética , Transtorno da Conduta/psicologia , Europa (Continente)/epidemiologia , Marcadores Genéticos , Humanos , Desequilíbrio de Ligação , Análise de Sequência com Séries de Oligonucleotídeos , Linhagem , Polimorfismo de Nucleotídeo Único , Escalas de Graduação PsiquiátricaRESUMO
BACKGROUND: The mesolimbic structures of the brain are important in the anticipation and perception of reward. Moreover, many drugs of addiction elicit their response in these structures. The M5 muscarinic receptor (M5R) is expressed in dopamine-containing neurones of the substantia nigra pars compacta and ventral tegmental area, and regulates the release of mesolimbic dopamine. Mice lacking M5R show a substantial reduction in both reward and withdrawal responses to morphine and cocaine. The CHRM5, the gene that codes for the M5R, is a strong biological candidate for a role in human addiction. We screened the coding and core promoter sequences of CHRM5 using denaturing high performance liquid chromatography to identify common polymorphisms. Additional polymorphisms within the coding and core promoter regions that were identified through dbSNP were validated in the test population. We investigated whether these polymorphisms influence substance dependence and dose in a cohort of 1947 young Australians. RESULTS: Analysis was performed on 815 participants of European ancestry who were interviewed at wave 8 of the cohort study and provided DNA. We observed a 26.8% increase in cigarette consumption in carriers of the rs7162140 T-allele, equating to 20.1 cigarettes per week (p=0.01). Carriers of the rs7162140 T-allele were also found to have nearly a 3-fold increased risk of developing cannabis dependence (OR=2.9 (95%CI 1.1-7.4); p=0.03). CONCLUSION: Our data suggest that variation within the CHRM5 locus may play an important role in tobacco and cannabis but not alcohol addiction in European ancestry populations. This is the first study to show an association between CHRM5 and substance use in humans. These data support the further investigation of this gene as a risk factor in substance use and dependence.
Assuntos
Consumo de Bebidas Alcoólicas/genética , Variação Genética , Abuso de Maconha/genética , Receptor Muscarínico M5/genética , Tabagismo/genética , Adolescente , Cromatografia Líquida de Alta Pressão , Estudos de Coortes , Frequência do Gene , Humanos , Polimorfismo de Nucleotídeo Único , Estudos Prospectivos , Vitória , População BrancaRESUMO
Coeliac disease (CD) is a chronic immune-mediated disease triggered by the ingestion of gluten. It has an estimated prevalence of approximately 1% in European populations. Specific HLA-DQA1 and HLA-DQB1 alleles are established coeliac susceptibility genes and are required for the presentation of gliadin to the immune system resulting in damage to the intestinal mucosa. In the largest association analysis of CD to date, 39 non-HLA risk loci were identified, 13 of which were new, in a sample of 12,014 individuals with CD and 12 228 controls using the Immunochip genotyping platform. Including the HLA, this brings the total number of known CD loci to 40. We have replicated this study in an independent Irish CD case-control population of 425 CD and 453 controls using the Immunochip platform. Using a binomial sign test, we show that the direction of the effects of previously described risk alleles were highly correlated with those reported in the Irish population, (P=2.2 × 10(-16)). Using the Polygene Risk Score (PRS) approach, we estimated that up to 35% of the genetic variance could be explained by loci present on the Immunochip (P=9 × 10(-75)). When this is limited to non-HLA loci, we explain a maximum of 4.5% of the genetic variance (P=3.6 × 10(-18)). Finally, we performed a meta-analysis of our data with the previous reports, identifying two further loci harbouring the ZNF335 and NIFA genes which now exceed genome-wide significance, taking the total number of CD susceptibility loci to 42.