RESUMO
The Biogenesis of Lysosome-Related Organelles Complex 1 (BLOC-1) is a protein complex containing the schizophrenia susceptibility factor dysbindin, which is encoded by the gene DTNBP1. However, mechanisms engaged by dysbindin defining schizophrenia susceptibility pathways have not been quantitatively elucidated. Here, we discovered prevalent and novel cellular roles of the BLOC-1 complex in neuronal cells by performing large-scale Stable Isotopic Labeling of Cells in Culture (SILAC) quantitative proteomics combined with genetic analyses in dysbindin-null mice (Mus musculus) and the genome of schizophrenia patients. We identified 24 proteins that associate with the BLOC-1 complex, many of which were altered in content/distribution in cells or tissues deficient in BLOC-1. New findings include BLOC-1 interactions with the COG complex, a Golgi apparatus tether, and antioxidant enzymes peroxiredoxins 1-2. Importantly, loci encoding eight of the 24 proteins are affected by genomic copy number variation in schizophrenia patients. Thus, our quantitative proteomic studies expand the functional repertoire of the BLOC-1 complex and provide insight into putative molecular pathways of schizophrenia susceptibility.
Assuntos
Proteínas de Transporte/genética , Estudos de Associação Genética/métodos , Predisposição Genética para Doença/genética , Proteínas do Tecido Nervoso/genética , Proteômica/métodos , Esquizofrenia/genética , Animais , Proteínas de Transporte/fisiologia , Linhagem Celular Tumoral , Disbindina , Proteínas Associadas à Distrofina , Células HEK293 , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Proteínas do Tecido Nervoso/fisiologia , Esquizofrenia/metabolismo , Esquizofrenia/patologiaRESUMO
Trisomy and tetrasomy of distal chromosome 15q have rarely been reported. Although most of the described patients have some learning difficulties and are overgrown, the phenotype associated with distal trisomy/tetrasomy 15q is uncertain due to the small numbers of reported cases and the common co-occurrence of additional chromosome deletions in many patients with trisomy 15q. We present five individuals with overgrowth, learning difficulties and increased dosage of distal 15q. Partial trisomy 15q was identified in four of these cases. Two were generated through recombination of a parental pericentric inversion and two were generated through malsegregation of a maternal balanced 14;15 reciprocal translocation. In all four cases the trisomy can be considered "pure" as the 14p and 15p monosomies will exert no phenotypic effect. Partial tetrasomy 15q, as the result of an analphoid supernumerary chromosome derived from an inverted duplication of distal 15q, was identified in the fifth patient. In addition to the overgrowth and learning difficulties, all five had a characteristic facial appearance and three had renal anomalies. The gestalt consists of a long, thin face with a prominent chin and nose. Renal anomalies included renal agenesis, horseshoe kidney, and hydronephrosis. We provide further support for a distinct "15q overgrowth syndrome" caused by either trisomy or tetrasomy resulting in increased dosage of distal 15q. In addition we propose that renal anomalies and a distinctive facial appearance be considered major features of this condition.
Assuntos
Anormalidades Múltiplas/genética , Aberrações Cromossômicas , Cromossomos Humanos Par 15 , Aneuploidia , Tamanho Corporal , Face/anormalidades , Saúde da Família , Feminino , Dosagem de Genes , Humanos , Nefropatias , Deficiências da Aprendizagem , Masculino , Linhagem , Fenótipo , SíndromeRESUMO
BACKGROUND: Phenotypic heterogeneity in autism has long been conjectured to be a major hindrance to the discovery of genetic risk factors, leading to numerous attempts to stratify children based on phenotype to increase power of discovery studies. This approach, however, is based on the hypothesis that phenotypic heterogeneity closely maps to genetic variation, which has not been tested. Our study examines the impact of subphenotyping of a well-characterized autism spectrum disorder (ASD) sample on genetic homogeneity and the ability to discover common genetic variants conferring liability to ASD. METHODS: Genome-wide genotypic data of 2576 families from the Simons Simplex Collection were analyzed in the overall sample and phenotypic subgroups defined on the basis of diagnosis, IQ, and symptom profiles. We conducted a family-based association study, as well as estimating heritability and evaluating allele scores for each phenotypic subgroup. RESULTS: Association analyses revealed no genome-wide significant association signal. Subphenotyping did not increase power substantially. Moreover, allele scores built from the most associated single nucleotide polymorphisms, based on the odds ratio in the full sample, predicted case status in subsets of the sample equally well and heritability estimates were very similar for all subgroups. CONCLUSIONS: In genome-wide association analysis of the Simons Simplex Collection sample, reducing phenotypic heterogeneity had at most a modest impact on genetic homogeneity. Our results are based on a relatively small sample, one with greater homogeneity than the entire population; if they apply more broadly, they imply that analysis of subphenotypes is not a productive path forward for discovering genetic risk variants in ASD.
Assuntos
Transtorno do Espectro Autista/genética , Transtorno Autístico/genética , Fenótipo , Transtorno do Espectro Autista/fisiopatologia , Transtorno do Espectro Autista/psicologia , Transtorno Autístico/fisiopatologia , Transtorno Autístico/psicologia , Família , Feminino , Predisposição Genética para Doença , Variação Genética , Estudo de Associação Genômica Ampla/métodos , Humanos , Masculino , Polimorfismo de Nucleotídeo ÚnicoRESUMO
BACKGROUND: Brain development follows a different trajectory in children with autism spectrum disorders (ASD) than in typically developing children. A proxy for neurodevelopment could be head circumference (HC), but studies assessing HC and its clinical correlates in ASD have been inconsistent. This study investigates HC and clinical correlates in the Simons Simplex Collection cohort. METHODS: We used a mixed linear model to estimate effects of covariates and the deviation from the expected HC given parental HC (genetic deviation). After excluding individuals with incomplete data, 7225 individuals in 1891 families remained for analysis. We examined the relationship between HC/genetic deviation of HC and clinical parameters. RESULTS: Gender, age, height, weight, genetic ancestry, and ASD status were significant predictors of HC (estimate of the ASD effect = .2 cm). HC was approximately normally distributed in probands and unaffected relatives, with only a few outliers. Genetic deviation of HC was also normally distributed, consistent with a random sampling of parental genes. Whereas larger HC than expected was associated with ASD symptom severity and regression, IQ decreased with the absolute value of the genetic deviation of HC. CONCLUSIONS: Measured against expected values derived from covariates of ASD subjects, statistical outliers for HC were uncommon. HC is a strongly heritable trait, and population norms for HC would be far more accurate if covariates including genetic ancestry, height, and age were taken into account. The association of diminishing IQ with absolute deviation from predicted HC values suggests HC could reflect subtle underlying brain development and warrants further investigation.
Assuntos
Transtorno Autístico/patologia , Cabeça/patologia , Característica Quantitativa Herdável , Adulto , Transtorno Autístico/diagnóstico , Transtorno Autístico/genética , Pesos e Medidas Corporais , Criança , Família , Feminino , Humanos , Inteligência/fisiologia , MasculinoRESUMO
We tested the hypothesis that de novo copy number variation (CNV) is associated with autism spectrum disorders (ASDs). We performed comparative genomic hybridization (CGH) on the genomic DNA of patients and unaffected subjects to detect copy number variants not present in their respective parents. Candidate genomic regions were validated by higher-resolution CGH, paternity testing, cytogenetics, fluorescence in situ hybridization, and microsatellite genotyping. Confirmed de novo CNVs were significantly associated with autism (P = 0.0005). Such CNVs were identified in 12 out of 118 (10%) of patients with sporadic autism, in 2 out of 77 (3%) of patients with an affected first-degree relative, and in 2 out of 196 (1%) of controls. Most de novo CNVs were smaller than microscopic resolution. Affected genomic regions were highly heterogeneous and included mutations of single genes. These findings establish de novo germline mutation as a more significant risk factor for ASD than previously recognized.
Assuntos
Transtorno Autístico/genética , Dosagem de Genes , Genoma Humano , Mutação , Síndrome de Asperger/genética , Estudos de Casos e Controles , Criança , Análise Citogenética , Feminino , Deleção de Genes , Duplicação Gênica , Predisposição Genética para Doença , Mutação em Linhagem Germinativa , Humanos , Hibridização in Situ Fluorescente , Masculino , Cadeias de Markov , Repetições de Microssatélites , Hibridização de Ácido Nucleico , Análise de Sequência com Séries de Oligonucleotídeos , Pais , IrmãosRESUMO
PURPOSE: Genome-wide telomere screening by fluorescence in situ hybridization (FISH) has revealed that approximately 6% of unexplained mental retardation is due to submicroscopic telomere imbalances. However, the use of FISH for telomere screening is labor intensive and time consuming, given that 41 telomeres are interrogated. We have evaluated the use of array-based Comparative Genomic Hybridization (aCGH) as a more efficient tool for identifying telomere rearrangements. METHODS: In this study, 102 individuals with unexplained mental retardation, with either normal or abnormal FISH results, were selected for a blinded retrospective study using aCGH. Results between the two methodologies were compared to ascertain the ability of aCGH to be used in a clinical diagnostics setting. RESULTS: We detected 100% of all imbalances previously identified by FISH (n = 17) and identified two additional abnormalities, a 10q telomere duplication and an interstitial duplication of 22q11. Interphase FISH analysis verified all abnormal array results. We also demonstrated that aCGH can accurately calibrate the size of telomere imbalances by using an array with "molecular rulers" for the telomeric regions of 1p, 16p, 17p, and 22q. CONCLUSION: This study demonstrates that aCGH is an equivalent methodology to telomere FISH for detecting submicroscopic deletions. In addition, small duplications that are not easily visible by FISH can be accurately detected using aCGH. Because aCGH allows simultaneous interrogation of hundreds to thousands of DNA probes and is more amenable to automation, it offers an efficient and high-throughput alternative for detecting and calibrating unbalanced rearrangements, both of the telomere region, as well as other genomic locations.
Assuntos
Aberrações Cromossômicas/estatística & dados numéricos , Análise Citogenética/métodos , Testes Genéticos/métodos , Deficiência Intelectual/genética , Telômero/genética , Estudos de Avaliação como Assunto , Humanos , Hibridização in Situ Fluorescente , Hibridização de Ácido Nucleico/métodos , Estudos RetrospectivosRESUMO
Miscarriage is a condition that affects 10%-15% of all clinically recognized pregnancies, most of which occur in the first trimester. Approximately 50% of first-trimester miscarriages result from fetal chromosome abnormalities. Currently, G-banded chromosome analysis is used to determine if large-scale genetic imbalances are the cause of these pregnancy losses. This technique relies on the culture of cells derived from the fetus, a technique that has many limitations, including a high rate of culture failure, maternal overgrowth of fetal cells, and poor chromosome morphology. Comparative genomic hybridization (CGH)-array analysis is a powerful new molecular cytogenetic technique that allows genomewide analysis of DNA copy number. By hybridizing patient DNA and normal reference DNA to arrays of genomic clones, unbalanced gains or losses of genetic material across the genome can be detected. In this study, 41 product-of-conception (POC) samples, which were previously analyzed by G-banding, were tested using CGH arrays to determine not only if the array could identify all reported abnormalities, but also whether any previously undetected genomic imbalances would be discovered. The array methodology detected all abnormalities as reported by G-banding analysis and revealed new abnormalities in 4/41 (9.8%) cases. Of those, one trisomy 21 POC was also mosaic for trisomy 20, one had a duplication of the 10q telomere region, one had an interstitial deletion of chromosome 9p, and the fourth had an interstitial duplication of the Prader-Willi/Angelman syndrome region on chromosome 15q, which, if maternally inherited, has been implicated in autism. This retrospective study demonstrates that the DNA-based CGH-array technology overcomes many of the limitations of routine cytogenetic analysis of POC samples while enhancing the detection of fetal chromosome aberrations.