title: Genetic control of individual differences in gene-specific methylation in human brain.
abstract: We have observed extensive interindividual differences in DNA methylation of 8590 CpG sites of 6229 genes in 153 human adult cerebellum samples, enriched in CpG island "shores" and at further distances from CpG islands. To search for genetic factors that regulate this variation, we performed a genome-wide association study (GWAS) mapping of methylation quantitative trait loci (mQTLs) for the 8590 testable CpG sites. cis association refers to correlation of methylation with SNPs within 1 Mb of a CpG site. 736 CpG sites showed phenotype-wide significant cis association with 2878 SNPs (after permutation correction for all tested markers and methylation phenotypes). In trans analysis of methylation, which tests for distant regulation effects, associations of 12 CpG sites and 38 SNPs remained significant after phenotype-wide correction. To examine the functional effects of mQTLs, we analyzed 85 genes that were with genetically regulated methylation we observed and for which we had quality gene expression data. Ten genes showed SNP-methylation-expression three-way associations-the same SNP simultaneously showed significant association with both DNA methylation and gene expression, while DNA methylation was significantly correlated with gene expression. Thus, we demonstrated that DNA methylation is frequently a heritable continuous quantitatively variable trait in human brain. Unlike allele-specific methylation, genetic polymorphisms mark both cis- and trans-regulatory genetic sites at measurable distances from their CpG sites. Some of the genetically regulated DNA methylation is directly connected with genetically regulated gene expression variation.
authors.affiliation: Department of Psychiatry and Behavioral Neuroscience, The University of Chicago, Chicago, IL 60637, USA.
authors.forename: Dandan
authors.initials: D
authors.lastname: Zhang
authors.forename: Lijun
authors.initials: L
authors.lastname: Cheng
authors.forename: Judith A
authors.initials: JA
authors.lastname: Badner
authors.forename: Chao
authors.initials: C
authors.lastname: Chen
authors.forename: Qi
authors.initials: Q
authors.lastname: Chen
authors.forename: Wei
authors.initials: W
authors.lastname: Luo
authors.forename: David W
authors.initials: DW
authors.lastname: Craig
authors.forename: Margot
authors.initials: M
authors.lastname: Redman
authors.forename: Elliot S
authors.initials: ES
authors.lastname: Gershon
authors.forename: Chunyu
authors.initials: C
authors.lastname: Liu
mesh_terms: D000328:Adult; D000368:Aged; D000483:Alleles; D001921:Brain / Q000378:metabolism*; D002531:Cerebellum / Q000378:metabolism; D018899:CpG Islands; D019175:DNA Methylation / Q000235:genetics*; D030561:Databases, Nucleic Acid; D005260:Female; D015870:Gene Expression; D055106:Genome-Wide Association Study; D006801:Humans; D008297:Male; D008875:Middle Aged; D020411:Oligonucleotide Array Sequence Analysis; D020641:Polymorphism, Single Nucleotide; D040641:Quantitative Trait Loci; D055815:Young Adult