Project description:Expression level of genes in lymphoblasts from individuals in three HapMap populations (CEU, CHB, JPT) were compared. More than 1,000 genes were found to be significantly different (Pc<0.05) in mean expression level between the CEU and CHB+JPT samples. Keywords: Comparison of Gene Expression Profiles from Lymphoblastoid cells
Project description:In addition to the differences between populations in transcriptional and translational regulation of genes, alternative pre-mRNA splicing (AS) is also likely to play an important role in regulating gene expression and generating variation in mRNA and protein isoforms. Recently, the genetic contribution to transcript isoform variation has been reported in individuals of recent European descent. We report here results of an investigation of the differences in AS patterns between human populations. AS patterns in 176 HapMap lymphoblastoid cell lines derived from individuals of European and African ancestry were evaluated using the Affymetrix GeneChip Human Exon 1.0 ST Array. A variety of biological processes such as immune response and mRNA metabolic process were found to be enriched among the differentially spliced genes. The differentially spliced genes also include some involved in human diseases that have different prevalence or susceptibility between populations. The genetic contribution to the population differences in transcript isoform variation was then evaluated by a genome-wide association using the HapMap genotypic data on single nucleotide polymorphisms (SNPs). The results suggest that local and distant genetic variants account for a substantial fraction of the observed transcript isoform variation between human populations. Exon level expression on 176 HapMap cell lines.
Project description:In addition to the differences between populations in transcriptional and translational regulation of genes, alternative pre-mRNA splicing (AS) is also likely to play an important role in regulating gene expression and generating variation in mRNA and protein isoforms. Recently, the genetic contribution to transcript isoform variation has been reported in individuals of recent European descent. We report here results of an investigation of the differences in AS patterns between human populations. AS patterns in 176 HapMap lymphoblastoid cell lines derived from individuals of European and African ancestry were evaluated using the Affymetrix GeneChip Human Exon 1.0 ST Array. A variety of biological processes such as immune response and mRNA metabolic process were found to be enriched among the differentially spliced genes. The differentially spliced genes also include some involved in human diseases that have different prevalence or susceptibility between populations. The genetic contribution to the population differences in transcript isoform variation was then evaluated by a genome-wide association using the HapMap genotypic data on single nucleotide polymorphisms (SNPs). The results suggest that local and distant genetic variants account for a substantial fraction of the observed transcript isoform variation between human populations.
Project description:Elucidating cytosine modification difference between human populations can enhance our understanding of ethnic specificity in complex traits such as disease predisposition and drug response. In this study, cytosine modification levels in 133 HapMap lymphoblastoid cell lines (LCLs) derived from individuals of European or African ancestry were profiled using the Illumina HumanMethylation450 BeadChip. Approximately 13% of the analyzed CpG sites showed differential modification between the two populations at false discovery rate (FDR) of 1%. CpG sites with greater modification levels in European descents were enriched in the proximal regulatory regions, while those greater in African descents were biased toward gene bodies. More than half of the detected population-specific cytosine modifications could be explained by genetic variation. A substantial proportion of local modification quantitative trait loci (mQTL) exhibited population-specific effects, suggesting that genetic epistasis and/or genotype × environment interaction could be common. Distinct inter-individual correlations were observed between gene expression and cytosine modifications in both proximal promoters and gene bodies, demonstrating a regulatory role of inter-individual variation in cytosine modification. Furthermore, a number of SNPs (single nucleotide polymorphisms) previously identified for complex traits with known racial disparities could be annotated as mQTLs for population-specific CpGs. Our findings revealed abundant population-specific cytosine modifications and the underlying genetic basis, as well as the relatively independent contribution of genetic and epigenetic variations to population differences in gene expression. 60 HapMap CEU and 73 HapMap YRI samples from Coriell Insitute were profiled for cytosine modification levels.
Project description:Expression level of genes in lymphoblasts from individuals in three HapMap populations (CEU, CHB, JPT) were compared. More than 1,000 genes were found to be significantly different (Pc<0.05) in mean expression level between the CEU and CHB+JPT samples. Experiment Overall Design: Gene expression analysis using Affymetrix Human Focus arrays; comparison of expression levels of genes by t-test.
Project description:B lymphoblastoid cell lines were obtained from Coriell Cell Repositories. Cell lines were grown according to Coriell guidelines and total RNA was extracted, labeled, and hybridized to an Affymetrix Human Genome Focus Array as previously described. We found extensive variation in gene-expression levels and estimate that ~83% of genes are differentially expressed among individuals and that ~17% of genes are differentially expressed among populations. By decomposing total gene-expression variation into within- versus among-population components, we find that most expression variation is due to variation among individuals rather than among populations, which parallels observations of extant patterns of human genetic variation. Experiment Overall Design: We used microarrays to survey patterns of natural gene expression variation in 16 HapMap individuals derived from the CEU and YRI samples.
Project description:Alternative pre-mRNA splicing increases proteomic diversity and provides a potential mechanism underlying both phenotypic diversity and susceptibility to genetic disorders in human populations. To investigate the variation in splicing among humans on a genomewide scale, we use a comprehensive exon-targeted microarray to examine alternative splicing in lymphoblasts derived from the CEPH HapMap population. We show the identification of transcripts containing annotated and novel sequence verified exon skipping, intron retention, and cryptic splice site usage that are specific between individuals. Using family-based linkage analysis, we demonstrate Mendelian inheritance and segregation of specific splice isoforms with regulatory haplotypes for three genes. Allelic association was further used to identify individual SNPs or regulatory haplotype blocks linked to the alternative splicing event, taking advantage of the high-resolution genotype information from the CEPH HapMap population. Keywords: Comparative genomic hybridiation within a 3 generation pedigree We used 14 individuals from the 3 generation CEPH/UTAH 1444 pedigree for our analysis of looking at heritability of differentially spliced exons within the family. 3 biological growths of individuals NA12739, NA12740, NA12750, and NA12751 were used and a single biological growth for the remaining 10 individuals.