Epigenetic Marks as Peripheral Biomarkers of Autism

描述（由申请人提供）：自闭症谱系障碍（ASD）是一种常见的表型，具有复杂的病因。虽然罕见的单个基因或基因组间隔可能足以导致ASD，但大多数患者可能将其疾病归因于遗传和环境变异的结合。连接遗传和环境影响的一个领域是表观遗传变异。为了寻找ASD特异性表观遗传变异的证据，我们筛选了49名ASD男性及其未受影响的父亲，检测807个基因对应的1505个CpG二核苷酸的甲基化状态。使用33对作为训练集，16对作为验证集，我们统计鉴定了116个差异甲基化位点（DML），这些位点具有最高的预测能力，可以将ASD男孩与其父亲区分开来。使用这些DML，我们以盲法筛选了另外29对ASD儿子/未受影响父亲的全血DNA，并正确分类了约80%的ASD患者。我们使用亚硫酸酯测序验证了这些基因座的一个子集，并排除了年龄依赖性的影响。为了进一步研究这一非同寻常的发现，我们建议进行一项全面的全基因组甲基化分析，对300个ASD Simons Simplex 4人家庭（父亲、母亲和不一致的男性同胞对）的全血DNA中与14000多个基因相关的27578个CpG二核苷酸进行分析。利用这些数据，我们将构建一个更小的定制DML集，并筛选额外的900个ASD先证及其家庭。该分析将直接验证我们的初步数据，并有可能确定可能损害ASD外周生物标志物测定的DML。

DESCRIPTION (provided by applicant): Autism spectrum disorders (ASD) are a common phenotype with a complex etiology. While a rare single gene or genomic interval may be sufficient to lead to ASD, most patients likely owe their disease to a combination of both genetic and environmental variation. One area that bridges genetic and environmental influences is epigenetic variation. Seeking evidence for epigenetic variation specific to ASD, we screened 49 ASD males and their unaffected fathers for methylation status of 1,505 CpG dinucleotides corresponding to 807 genes. Using 33 pairs as a training set and 16 pairs as a validation set, we statistically identified 116 differentially methylated loci (DML) that gave the highest predictive power to classify ASD boys from their fathers. Using these DML, we screened, in a blinded fashion, DNA isolated from whole blood in an additional 29 ASD son/unaffected father pairs and correctly classified ~80% of the ASD affected individuals. We validated a subset of these loci using bisulfite sequencing and ruled out age-dependent effects. To follow-up on this extraordinary observation, we propose here to conduct a comprehensive genome-wide methylation analysis that will interrogate 27,578 CpG dinucleotides associated with more than 14,000 genes in DNA isolated from whole blood in 300 ASD Simons Simplex 4-person families (father, mother and discordant male sib pair). Using this data, we will then construct a smaller custom set of DML and screen an additional 900 ASD probands and their families. This analysis will directly test our provocative preliminary data and potentially identify DML that could compromise a peripheral biomarker assay for ASD. PUBLIC HEALTH RELEVANCE: Autism is a common disorder whose causes are poorly understood. Both genetic and environmental influences are thought to act together causing autism. Epigenetics is an area that bridges genetic and environmental influencing and commonly is studied by examining dynamic methylation changes to the DNA. We have screened a total of 78 autistic boys and their fathers by this method in 807 genes and find 116 methylation changes that together can correctly identify nearly 80% of the affected boys from their fathers. We propose to confirm these exciting data in a much larger set of genes in 1,200 autistic boys and their families, including unaffected brothers. These data not only could provide new insight into the causes of autism but could also result in a screening test for autism. )