Project description:The exploration of quantitative variation in human populations has become one of the major priorities for medical genetics. The successful identification of variants that contribute to complex traits is highly dependent on reliable assays and genetic maps. We have performed a genome-wide quantitative trait analysis of 630 genes in 60 unrelated Utah residents with ancestry from Northern and Western Europe (CEPH) using the publicly available phase I data of the International HapMap project. The genes are located in regions of the human genome with elevated functional annotation and disease interest including the ENCODE regions spanning 1% of the genome, chromosome 21 and chromosome 20q12-13.2. We apply three different methods of multiple test correction, including Bonferroni, False Discovery Rate and permutations. For the 374 expressed genes, we find many regions with statistically significant association of SNPs with expression variation in lymphoblastoid cell lines after correcting for multiple tests. Based on our analyses, the signal proximal (cis-) to the genes of interest is more abundant and more stable than distal and trans across statistical methodologies. Our results suggest that regulatory polymorphism is widespread in the human genome and show that the 5 kb (phase I) HapMap has sufficient density to enable linkage disequilibrium mapping in humans. Such studies will significantly enhance our ability to annotate the non-coding part of the genome and interpret functional variation. In addition, we demonstrate that the HapMap cell lines themselves may serve as a useful resource for quantitative measurements at the cellular level. Keywords: Gene expression, Lymphoblastoid,
Project description:Ethnic differences in human DNA methylation have been shown for a number of CpG sites, but the genome-wide patterns and extent of these differences are unknown. In addition, whether the genetic control of polymorphic DNA methylation is population-specific has not been investigated. Here we measure DNA methylation near the transcription start sites of over 14,000 genes in 180 cell lines derived from one African and one European population. We find population-specific patterns of DNA methylation at over a third of all genes. Furthermore, although the methylation at over a thousand CpG sites is heritable, these heritabilities are also distinctly different between populations, suggesting extensive divergence in the genetic control of DNA methylation. In support of this, genetic mapping of DNA methylation reveals that there is also little overlap in genetic associations between populations. This population-specificity is supported by the patterns of DNA methylation in several hundred brain samples, suggesting it holds in vivo and across tissues. These results suggest that DNA methylation is highly divergent between populations, and that this divergence may be due in large part to complex epistasis or gene x environment interactions. Genomic DNA from 180 lymphoblastoid cell lines were bisulphite converted and hybridized, along with 8 additional technical replicates, to the Illumina Infinium HumanMethylation27 Beadchip v1.2 for genome-wide DNA methylation profiling. The cell lines were derived from two HapMap populations: 'CEPH (Utah residents with ancestry from northern and western Europe)' (CEU) and 'Yoruba in Ibadan, Nigeria' (YRI).
Project description:This is the validation data for candidate de novo CNV calls made in the CEU Hapmap by Itsara et al., Genome Research 2010. In this study, de novo CNV calls were initially made with Illumina 1M SNP arrays. Validation of CNV calls was performed with Nimblegen custom array CGH using the extended CEPH pedigrees. A truly de novo CNV would be unobserved in the first generation (CEU trio parents), validated in the second generation (CEU trio children), and assuming no selective effects, transmitted to approximately half of the individuals in the third generation. We attempted validation of 4 de novo CNVs in 3 extended CEPH pedigrees: 1358, 1408, and 1459.
Project description:Baseline expression levels of genes in CEPH individuals from the International HapMap Project were measured using the Affymetrix Human Genome Focus Arrays. Arrays were analyzed using MAS 5.0 software (Affymetrix).
Project description:This is the validation data for candidate de novo CNV calls made in the CEU Hapmap by Itsara et al., Genome Research 2010. In this study, de novo CNV calls were initially made with Illumina 1M SNP arrays. Validation of CNV calls was performed with Nimblegen custom array CGH using the extended CEPH pedigrees. A truly de novo CNV would be unobserved in the first generation (CEU trio parents), validated in the second generation (CEU trio children), and assuming no selective effects, transmitted to approximately half of the individuals in the third generation. We attempted validation of 4 de novo CNVs in 3 extended CEPH pedigrees: 1358, 1408, and 1459. 12 samples were hybridized in each of the three pedigrees (36 samples total) against a previously well-characterized reference (GM15510; see Tuzun et al., Nat Genet 2005).