RESUMEN
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.
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Trastorno del Espectro Autista , Trastornos Mentales , Bancos de Muestras Biológicas , Cerebelo , Predisposición Genética a la Enfermedad/genética , Estudio de Asociación del Genoma Completo , Humanos , Trastornos Mentales/genética , Polimorfismo de Nucleótido Simple/genética , Reino UnidoRESUMEN
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.
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Trastorno Autístico/genética , Trastorno Autístico/fisiopatología , Trastorno Autístico/terapia , Predisposición Genética a la Enfermedad , Técnicas de Genotipaje , HumanosRESUMEN
Sleep disturbances are common in attention deficit hyperactivity disorder (ADHD) and associated with poor outcomes. We tested whether, in children with ADHD, (1) polygenic liability for sleep phenotypes is over- or under-transmitted from parents, (2) this liability is linked to comorbid sleep disturbances, and (3) ADHD genetic risk is associated with comorbid sleep disturbances. We derived polygenic scores (PGS) for insomnia, chronotype, sleep duration, and ADHD, in 758 children (5-18 years old) diagnosed with ADHD and their parents. We conducted polygenic transmission disequilibrium tests for each sleep PGS in complete parent-offspring ADHD trios (N = 328) and an independent replication sample of ADHD trios (N = 844). Next, we tested whether insomnia, sleep duration, and ADHD PGS were associated with co-occurring sleep phenotypes (hypersomnia, insomnia, restless sleep, poor sleep quality, and nightmares) in children with ADHD. Children's insomnia and chronotype PGS did not differ from mid-parent average PGS but long sleep duration PGS were significantly over-transmitted to children with ADHD. This was supported by a combined analysis using the replication sample. Insomnia, sleep duration, and ADHD PGS were not associated with comorbid sleep disturbances. There is weak evidence that children with ADHD over-inherit polygenic liability for longer sleep duration and do not differentially inherit polygenic liability for insomnia or chronotype. There was insufficient evidence that childhood sleep disturbances were driven by polygenic liability for ADHD or sleep traits, suggesting that sleep disturbances in ADHD may be aetiologically different to general population sleep phenotypes and do not index greater ADHD genetic risk burden.
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Trastorno por Déficit de Atención con Hiperactividad , Trastornos del Inicio y del Mantenimiento del Sueño , Trastornos del Sueño-Vigilia , Humanos , Trastorno por Déficit de Atención con Hiperactividad/epidemiología , Trastorno por Déficit de Atención con Hiperactividad/genética , Trastorno por Déficit de Atención con Hiperactividad/diagnóstico , Trastornos del Inicio y del Mantenimiento del Sueño/epidemiología , Trastornos del Inicio y del Mantenimiento del Sueño/genética , Sueño , Fenotipo , Trastornos del Sueño-Vigilia/epidemiología , Trastornos del Sueño-Vigilia/genéticaRESUMEN
Cognitive abilities are one of the major transdiagnostic domains in the National Institute of Mental Health's Research Domain Criteria (RDoC). Following RDoC's integrative approach, we aimed to develop brain-based predictive models for cognitive abilities that (a) are developmentally stable over years during adolescence and (b) account for the relationships between cognitive abilities and socio-demographic, psychological and genetic factors. For this, we leveraged the unique power of the large-scale, longitudinal data from the Adolescent Brain Cognitive Development (ABCD) study (n ~ 11 k) and combined MRI data across modalities (task-fMRI from three tasks: resting-state fMRI, structural MRI and DTI) using machine-learning. Our brain-based, predictive models for cognitive abilities were stable across 2 years during young adolescence and generalisable to different sites, partially predicting childhood cognition at around 20% of the variance. Moreover, our use of 'opportunistic stacking' allowed the model to handle missing values, reducing the exclusion from around 80% to around 5% of the data. We found fronto-parietal networks during a working-memory task to drive childhood-cognition prediction. The brain-based, predictive models significantly, albeit partially, accounted for variance in childhood cognition due to (1) key socio-demographic and psychological factors (proportion mediated = 18.65% [17.29%-20.12%]) and (2) genetic variation, as reflected by the polygenic score of cognition (proportion mediated = 15.6% [11%-20.7%]). Thus, our brain-based predictive models for cognitive abilities facilitate the development of a robust, transdiagnostic research tool for cognition at the neural level in keeping with the RDoC's integrative framework.
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Encéfalo , Cognición , Adolescente , Humanos , Encéfalo/diagnóstico por imagen , Mapeo Encefálico , Imagen por Resonancia Magnética , DemografíaRESUMEN
The majority of common risk alleles identified for neuropsychiatric disorders reside in noncoding regions of the genome and are therefore likely to impact gene regulation. However, the genes that are primarily affected and the nature and developmental timing of these effects remain unclear. Given the hypothesized role for early neurodevelopmental processes in these conditions, we here define genetic predictors of gene expression in the human fetal brain with which we perform transcriptome-wide association studies (TWASs) of attention deficit hyperactivity disorder (ADHD), autism spectrum disorder, bipolar disorder, major depressive disorder, and schizophrenia. We identify prenatal cis-regulatory effects on 63 genes and 166 individual transcripts associated with genetic risk for these conditions. We observe pleiotropic effects of expression predictors for a number of genes and transcripts, including those of decreased DDHD2 expression in association with risk for schizophrenia and bipolar disorder, increased expression of a ST3GAL3 transcript with risk for schizophrenia and ADHD, and increased expression of an XPNPEP3 transcript with risk for schizophrenia, bipolar disorder, and major depression. For the protocadherin alpha cluster genes PCDHA7 and PCDHA8, we find that predictors of low expression are associated with risk for major depressive disorder while those of higher expression are associated with risk for schizophrenia. Our findings support a role for altered gene regulation in the prenatal brain in susceptibility to various neuropsychiatric disorders and prioritize potential risk genes for further neurobiological investigation.
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Trastorno por Déficit de Atención con Hiperactividad , Trastorno del Espectro Autista , Trastorno Depresivo Mayor , Trastorno por Déficit de Atención con Hiperactividad/genética , Trastorno del Espectro Autista/genética , Encéfalo , Trastorno Depresivo Mayor/genética , Femenino , Expresión Génica , Predisposición Genética a la Enfermedad/genética , Estudio de Asociación del Genoma Completo , Humanos , Fosfolipasas , EmbarazoRESUMEN
Psychiatric disorders show phenotypic as well as genetic overlaps. There are however also marked developmental changes throughout childhood. We investigated the extent to which, for a full range of early childhood psychopathology, a general "p" factor was explained by genetic liability, as indexed by multiple different psychiatric polygenic risk scores (PRS) and whether these relationships altered with age. The sample was a UK, prospective, population-based cohort with psychopathology data at age 7 (N = 8161) and age 13 (N = 7017). PRS were generated from large published genome-wide association studies. At both ages, we found evidence for a childhood "p" factor as well as for specific factors. Schizophrenia and attention-deficit/hyperactivity disorder (ADHD) PRS were associated with this general "p" factor at both ages but depression and autism spectrum disorder (ASD) PRS were not. We also found some evidence of associations between schizophrenia, ADHD and depression PRS with specific factors, but these were less robust and there was evidence for developmental changes.
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Trastornos Mentales/genética , Psicopatología/métodos , Adolescente , Trastorno por Déficit de Atención con Hiperactividad/diagnóstico , Trastorno por Déficit de Atención con Hiperactividad/genética , Trastorno del Espectro Autista/diagnóstico , Trastorno del Espectro Autista/genética , Niño , Estudios de Cohortes , Depresión/diagnóstico , Depresión/genética , Femenino , Predisposición Genética a la Enfermedad/genética , Estudio de Asociación del Genoma Completo/métodos , Humanos , Estudios Longitudinales , Masculino , Trastornos Mentales/fisiopatología , Herencia Multifactorial/genética , Estudios Prospectivos , Factores de Riesgo , Esquizofrenia/diagnóstico , Esquizofrenia/genética , Reino Unido/epidemiologíaRESUMEN
There is increasing evidence that childhood Attention-Deficit Hyperactivity Disorder (ADHD) elevates risk of later depression, but the mechanisms behind this association are unclear. We investigated the relationship between childhood ADHD symptoms and late-adolescent depressive symptoms in a population cohort, and examined whether academic attainment and peer problems mediated this association. ALSPAC (Avon Longitudinal Study of Parents and Children) is an ongoing prospective longitudinal population-based UK cohort that has collected data since September 1990. 2950 individuals with data on parent-reported ADHD symptoms in childhood (7.5 years) and self-reported depressive symptoms in late adolescence (17.5 years) were included in analyses. 2161 individuals with additional data at age 16 years on parent-reported peer problems as an indicator of peer relationships and formal examination results (General Certificate of Secondary Education; GCSE) as an indicator of academic attainment were included in mediation analyses. Childhood ADHD symptoms were associated with higher depressive symptoms (b = 0.49, SE = 0.11, p < 0.001) and an increased odds of clinically significant depressive symptoms in adolescence (OR = 1.27, 95% CI 1.15-1.41, p < 0.001). The association with depressive symptoms was mediated in part by peer problems and academic attainment which accounted for 14.68% and 20.13% of the total effect, respectively. Childhood ADHD is associated with increased risk of later depression. The relationship is mediated in part by peer relationships and academic attainment. This highlights peer relationships and academic attainment as potential targets of depression prevention and intervention in those with ADHD. Future research should investigate which aspects of peer relationships are important in conferring later risk for depression.
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Trastorno por Déficit de Atención con Hiperactividad/complicaciones , Depresión/etiología , Éxito Académico , Adolescente , Niño , Femenino , Humanos , Relaciones Interpersonales , Estudios Longitudinales , Masculino , Estudios ProspectivosRESUMEN
BACKGROUND: The past decade has seen the development of services for adults presenting with symptoms of autism spectrum disorder (ASD) in the UK. Compared with children, little is known about the phenotypic and genetic characteristics of these patients. AIMS: This e-cohort study aimed to examine the phenotypic and genetic characteristics of a clinically presenting sample of adults diagnosed with ASD by specialist services. METHOD: Individuals diagnosed with ASD as adults were recruited by the National Centre for Mental Health and completed self-report questionnaires, interviews and provided DNA; 105 eligible individuals were matched to 76 healthy controls. We investigated demographics, social history and comorbid psychiatric and physical disorders. Samples were genotyped, copy number variants (CNVs) were called and polygenic risk scores were calculated. RESULTS: Of individuals with ASD, 89.5% had at least one comorbid psychiatric diagnosis, with depression (62.9%) and anxiety (55.2%) being the most common. The ASD group experienced more neurological comorbidities than controls, particularly migraine headache. They were less likely to have married or be in work, and had more alcohol-related problems. There was a significantly higher load of autism common genetic variants in the adult ASD group compared with controls, but there was no difference in the rate of rare CNVs. CONCLUSIONS: This study provides important information about psychiatric comorbidity in adult ASD, which may inform clinical practice and patient counselling. It also suggests that the polygenic load of common ASD-associated variants may be important in conferring risk within the non-intellectually disabled population of adults with ASD. DECLARATION OF INTEREST: None.
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Trastorno del Espectro Autista , Adulto , Trastorno del Espectro Autista/diagnóstico , Trastorno del Espectro Autista/epidemiología , Trastorno del Espectro Autista/genética , Niño , Estudios de Cohortes , Comorbilidad , Genotipo , Humanos , FenotipoRESUMEN
Multiple genome-wide association studies of schizophrenia have implicated genetic variants within the gene encoding microRNA-137. As risk variants within or regulated by MIR137 have been implicated in memory performance, we investigated the additive effects of schizophrenia-associated risk variants in genes empirically regulated by MIR137 on brain regions associated with memory function. A polygenic risk score (PRS) was calculated (at a p = 0.05 threshold), using this empirically regulated MIR137 gene set, to investigate associations between this PRS and structural brain measures. These measures included total brain volume, cortical thickness, cortical surface area, and hippocampal volume, in a sample of 216 individuals consisting of healthy participants (n = 171) and patients with psychosis (n = 45). We did not observe a significant association between MIR137 PRS and these cortical thickness, surface area or hippocampal volume measures linked to memory function; a significant association between increasing PRS and decreasing total brain volume, independent of diagnosis status (R2 = 0.008, Beta = -0.09, p = 0.029), was observed. This did not survive correction for multiple testing. In conclusion, our study yielded only suggestive evidence that risk variants interacting with MIR137 impacts on cortical structure.
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Encéfalo/patología , MicroARNs/genética , Esquizofrenia/genética , Adulto , Encéfalo/metabolismo , Femenino , Predisposición Genética a la Enfermedad , Estudio de Asociación del Genoma Completo , Humanos , Masculino , Herencia Multifactorial , Pruebas Neuropsicológicas , Polimorfismo de Nucleótido Simple , Trastornos Psicóticos/genética , Trastornos Psicóticos/metabolismo , Trastornos Psicóticos/patología , Factores de Riesgo , Esquizofrenia/metabolismo , Esquizofrenia/patologíaRESUMEN
Sprouty proteins are regulators of cell growth and branching morphogenesis. Unlike mouse Spry3, which is X-linked, human SPRY3 maps to the pseudoautosomal region 2; however, the human Y-linked allele is not expressed due to epigenetic silencing by an unknown mechanism. SPRY3 maps adjacent to X-linked Trimethyllysine hydroxylase epsilon (TMLHE), recently identified as an autism susceptibility gene. We report that Spry3 is highly expressed in central and peripheral nervous system ganglion cells in mouse and human, including cerebellar Purkinje cells and retinal ganglion cells. Transient over-expression or knockdown of Spry3 in cultured mouse superior cervical ganglion cells inhibits and promotes, respectively, neurite growth and branching. A 0.7 kb gene fragment spanning the human SPRY3 transcriptional start site recapitulates the endogenous Spry3-expression pattern in LacZ reporter mice. In the human and mouse the SPRY3 promoter contains an AG-rich repeat and we found co-expression, and promoter binding and/or regulation of SPRY3 expression by transcription factors MAZ, EGR1, ZNF263 and PAX6. We identified eight alleles of the human SPRY3 promoter repeat in Caucasians, and similar allele frequencies in autism families. We characterized multiple SPRY3 transcripts originating at two CpG islands in the X-linked F8A3-TMLHE region, suggesting X chromosome regulation of SPRY3. These findings provide an explanation for differential regulation of X and Y-linked SPRY3 alleles. In addition, the presence of a SPRY3 transcript exon in a previously described X chromosome deletion associated with autism, and the cerebellar interlobular variation in Spry3 expression coincident with the reported pattern of Purkinje cell loss in autism, suggest SPRY3 as a candidate susceptibility locus for autism.
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Trastorno Autístico/genética , Cromosomas Humanos X , Predisposición Genética a la Enfermedad , Péptidos y Proteínas de Señalización Intracelular/genética , Regiones Promotoras Genéticas , Receptor PAR-2/genética , Alelos , Animales , Composición de Base , Secuencia de Bases , Línea Celular , Cerebelo/metabolismo , Islas de CpG , Metilación de ADN , Modelos Animales de Enfermedad , Exones , Ganglios/metabolismo , Expresión Génica , Regulación de la Expresión Génica , Genes Ligados a X , Sitios Genéticos , Humanos , Ratones , Ratones Transgénicos , Datos de Secuencia Molecular , Neuritas/metabolismo , Polimorfismo Genético , Alineación de Secuencia , Factores de Transcripción/metabolismo , Transcripción GenéticaRESUMEN
Rare copy-number variation (CNV) is an important source of risk for autism spectrum disorders (ASDs). We analyzed 2,446 ASD-affected families and confirmed an excess of genic deletions and duplications in affected versus control groups (1.41-fold, p = 1.0 × 10(-5)) and an increase in affected subjects carrying exonic pathogenic CNVs overlapping known loci associated with dominant or X-linked ASD and intellectual disability (odds ratio = 12.62, p = 2.7 × 10(-15), â¼3% of ASD subjects). Pathogenic CNVs, often showing variable expressivity, included rare de novo and inherited events at 36 loci, implicating ASD-associated genes (CHD2, HDAC4, and GDI1) previously linked to other neurodevelopmental disorders, as well as other genes such as SETD5, MIR137, and HDAC9. Consistent with hypothesized gender-specific modulators, females with ASD were more likely to have highly penetrant CNVs (p = 0.017) and were also overrepresented among subjects with fragile X syndrome protein targets (p = 0.02). Genes affected by de novo CNVs and/or loss-of-function single-nucleotide variants converged on networks related to neuronal signaling and development, synapse function, and chromatin regulation.
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Trastornos Generalizados del Desarrollo Infantil/genética , Variaciones en el Número de Copia de ADN , Redes y Vías Metabólicas/genética , Niño , Femenino , Redes Reguladoras de Genes , Humanos , Masculino , Familia de Multigenes , Linaje , Eliminación de SecuenciaRESUMEN
The autism spectrum disorders (ASDs) are a group of conditions characterized by impairments in reciprocal social interaction and communication, and the presence of restricted and repetitive behaviours. Individuals with an ASD vary greatly in cognitive development, which can range from above average to intellectual disability. Although ASDs are known to be highly heritable ( approximately 90%), the underlying genetic determinants are still largely unknown. Here we analysed the genome-wide characteristics of rare (<1% frequency) copy number variation in ASD using dense genotyping arrays. When comparing 996 ASD individuals of European ancestry to 1,287 matched controls, cases were found to carry a higher global burden of rare, genic copy number variants (CNVs) (1.19 fold, P = 0.012), especially so for loci previously implicated in either ASD and/or intellectual disability (1.69 fold, P = 3.4 x 10(-4)). Among the CNVs there were numerous de novo and inherited events, sometimes in combination in a given family, implicating many novel ASD genes such as SHANK2, SYNGAP1, DLGAP2 and the X-linked DDX53-PTCHD1 locus. We also discovered an enrichment of CNVs disrupting functional gene sets involved in cellular proliferation, projection and motility, and GTPase/Ras signalling. Our results reveal many new genetic and functional targets in ASD that may lead to final connected pathways.
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Trastornos Generalizados del Desarrollo Infantil/genética , Trastornos Generalizados del Desarrollo Infantil/fisiopatología , Variaciones en el Número de Copia de ADN/genética , Dosificación de Gen/genética , Predisposición Genética a la Enfermedad/genética , Estudios de Casos y Controles , Movimiento Celular , Niño , Trastornos Generalizados del Desarrollo Infantil/patología , Citoprotección , Europa (Continente)/etnología , Estudio de Asociación del Genoma Completo , Humanos , Transducción de Señal , Conducta SocialRESUMEN
While it is apparent that rare variation can play an important role in the genetic architecture of autism spectrum disorders (ASDs), the contribution of common variation to the risk of developing ASD is less clear. To produce a more comprehensive picture, we report Stage 2 of the Autism Genome Project genome-wide association study, adding 1301 ASD families and bringing the total to 2705 families analysed (Stages 1 and 2). In addition to evaluating the association of individual single nucleotide polymorphisms (SNPs), we also sought evidence that common variants, en masse, might affect the risk. Despite genotyping over a million SNPs covering the genome, no single SNP shows significant association with ASD or selected phenotypes at a genome-wide level. The SNP that achieves the smallest P-value from secondary analyses is rs1718101. It falls in CNTNAP2, a gene previously implicated in susceptibility for ASD. This SNP also shows modest association with age of word/phrase acquisition in ASD subjects, of interest because features of language development are also associated with other variation in CNTNAP2. In contrast, allele scores derived from the transmission of common alleles to Stage 1 cases significantly predict case status in the independent Stage 2 sample. Despite being significant, the variance explained by these allele scores was small (Vm< 1%). Based on results from individual SNPs and their en masse effect on risk, as inferred from the allele score results, it is reasonable to conclude that common variants affect the risk for ASD but their individual effects are modest.
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Trastornos Generalizados del Desarrollo Infantil/genética , Predisposición Genética a la Enfermedad , Estudio de Asociación del Genoma Completo , Proteínas de la Membrana/genética , Proteínas del Tejido Nervioso/genética , Alelos , Niño , Trastornos Generalizados del Desarrollo Infantil/fisiopatología , Femenino , Frecuencia de los Genes , Genotipo , Humanos , Desarrollo del Lenguaje , Masculino , Polimorfismo de Nucleótido Simple , Factores de RiesgoRESUMEN
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.
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Proteínas Adaptadoras Transductoras de Señales/genética , Proteína Quinasa Tipo 4 Dependiente de Calcio Calmodulina/genética , Trastornos Generalizados del Desarrollo Infantil/genética , Proteína de la Discapacidad Intelectual del Síndrome del Cromosoma X Frágil/genética , Predisposición Genética a la Enfermedad , Polimorfismo de Nucleótido Simple , Proteínas Adaptadoras Transductoras de Señales/metabolismo , Adolescente , Alelos , Proteína Quinasa Tipo 4 Dependiente de Calcio Calmodulina/metabolismo , Niño , Trastornos Generalizados del Desarrollo Infantil/etnología , Trastornos Generalizados del Desarrollo Infantil/metabolismo , Trastornos Generalizados del Desarrollo Infantil/patología , Preescolar , Femenino , Proteína de la Discapacidad Intelectual del Síndrome del Cromosoma X Frágil/metabolismo , Regulación de la Expresión Génica , Técnicas de Genotipaje , Humanos , Masculino , Plasticidad Neuronal/genética , Unión Proteica , Factores de Riesgo , Transducción de Señal , Población BlancaRESUMEN
Recent research has highlighted the role of complement genes in shaping the microstructure of the brain during early development, and in contributing to common allele risk for Schizophrenia. We hypothesised that common risk variants for schizophrenia within complement genes will associate with structural changes in white matter microstructure within tracts innervating the frontal lobe. Results showed that risk alleles within the complement gene set, but also intergenic alleles, significantly predict axonal density in white matter tracts connecting frontal cortex with parietal, temporal and occipital cortices. Specifically, risk alleles within the Major Histocompatibility Complex region in chromosome 6 appeared to drive these associations. No significant associations were found for the orientation dispersion index. These results suggest that changes in axonal packing - but not in axonal coherence - determined by common risk alleles within the MHC genomic region - including variants related to the Complement system - appear as a potential neurobiological mechanism for schizophrenia.
Asunto(s)
Alelos , Predisposición Genética a la Enfermedad , Complejo Mayor de Histocompatibilidad , Esquizofrenia , Sustancia Blanca , Humanos , Esquizofrenia/genética , Esquizofrenia/patología , Sustancia Blanca/patología , Sustancia Blanca/diagnóstico por imagen , Femenino , Masculino , Adulto , Complejo Mayor de Histocompatibilidad/genética , Adulto Joven , Lóbulo Frontal/patología , Lóbulo Frontal/diagnóstico por imagen , Persona de Mediana Edad , Imagen de Difusión Tensora , Cromosomas Humanos Par 6/genética , Axones/patología , Polimorfismo de Nucleótido SimpleRESUMEN
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.
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Simulación por Computador , Estudio de Asociación del Genoma Completo , Modelos Teóricos , Estudios de Casos y Controles , Genotipo , Humanos , Fenotipo , Proyectos de InvestigaciónRESUMEN
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.
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Trastorno Autístico/genética , Predisposición Genética a la Enfermedad , Variación Genética , Esquizofrenia/genética , Estudios de Casos y Controles , Marcadores Genéticos , Humanos , Herencia Multifactorial/genética , Factores de RiesgoRESUMEN
Background: Copy number variations (CNVs) conferring risk for mental disorders are associated with brain changes and cognitive deficits. However, whether these effects are shared or distinct across CNVs remains untested. Here we compared the effects on brain morphometry and cognitive performance across CNVs with shared psychiatric liability. Methods: Unaffected and unrelated participants of White British and Irish ancestry were drawn from the UK Biobank. After quality control, we retained 31,941 participants not carrying any damaging CNVs and 202 participants carrying one CNV increasing risk for schizophrenia. Using regression analyses, we tested the association between brain morphometry and cognitive performance with CNV carrying status and compared these effect sizes across CNVs using z test for the equality of regression coefficients. Equation modeling was used to examine the mediation of brain phenotypes on the association between CNVs and cognitive performance. Results: We detected different patterns of association between CNVs and brain morphometry and cognitive abilities. Comparing across CNVs, 1q21.1 deletion showed the strongest association with surface area in frontal lobe (ß = -1.03, p = 4 × 10-8; ß = -0.81, p = .00001) and performance in digit memory (ß = -1.58, p = .00003), while 1q21.1 duplication showed the strongest association with volume of the putamen (ß = -0.70, p = .0004) and reaction time (ß = -1.14, p = .000002). We also showed that even when 2 CNVs were associated with performance in the same cognitive ability, these associations were mediated by different brain changes. Conclusions: Despite sharing similar psychiatric liability, the CNVs under study appeared to have different effects on brain morphometry and on performance in cognitive abilities, suggesting the existence of distinctive neurobiological pathways into the same clinical phenotypes.
RESUMEN
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.
Asunto(s)
Trastorno por Déficit de Atención con Hiperactividad , Trastorno de la Conducta , Síndrome de Tourette , Humanos , Trastorno por Déficit de Atención con Hiperactividad/epidemiología , Herencia Multifactorial/genética , Síndrome de Tourette/genética , Trastorno de la Conducta/psicología , PadresRESUMEN
BACKGROUND: Parental depression is a common and potent risk factor for depression in offspring. However, the developmental course of depression from childhood to early-adulthood has not been characterized in this high-risk group. METHODS: Using longitudinal data from 337 young people who had a parent with a history of recurrent major depressive disorder (MDD), we characterized trajectories of broadly defined depressive disorder using latent class growth analysis. We used clinical descriptions to further characterise trajectory classes. RESULTS: Two trajectory classes were identified: childhood-emerging (25 %) and adulthood-emerging (75 %). The childhood-emerging class showed high rates of depressive disorder from age 12.5, which persisted through the study period. The adulthood-emerging class showed low rates of depressive disorder until age 26. Individual factors (IQ and ADHD symptoms) and parent depression severity (comorbidity, persistence and impairment) differentiated the classes but there were no differences in family history score or polygenic scores associated with psychiatric disorder. Clinical descriptions indicated functional impairment in both classes, but more severe symptomatology and impairment in the childhood-emerging class. LIMITATIONS: Attrition particularly affected participation in young adulthood. Factors associated with attrition were low family income, single parent household status and low parental education. CONCLUSIONS: The developmental course of depressive disorder in children of depressed parents is variable. When followed up to adult life, most individuals exhibited some functional impairment. An earlier age-of-onset was associated with a more persistent and impairing course of depression. Access to effective prevention strategies is particularly warranted for at-risk young people showing early-onsetting and persistent depressive symptoms.