Journal Article

Gene expression variation and expression quantitative trait mapping of human chromosome 21 genes

Samuel Deutsch, Robert Lyle, Emmanouil T. Dermitzakis, Homa Attar, Lakshman Subrahmanyan, Corinne Gehrig, Leila Parand, Maryline Gagnebin, Jacques Rougemont, C. Victor Jongeneel and Stylianos E. Antonarakis

in Human Molecular Genetics

Volume 14, issue 23, pages 3741-3749
Published in print December 2005 | ISSN: 0964-6906
Published online October 2005 | e-ISSN: 1460-2083 | DOI: http://dx.doi.org/10.1093/hmg/ddi404
Gene expression variation and expression quantitative trait mapping of human chromosome 21 genes

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Inter-individual differences in gene expression are likely to account for an important fraction of phenotypic differences, including susceptibility to common disorders. Recent studies have shown extensive variation in gene expression levels in humans and other organisms, and that a fraction of this variation is under genetic control. We investigated the patterns of gene expression variation in a 25 Mb region of human chromosome 21, which has been associated with many Down syndrome (DS) phenotypes. Taqman real-time PCR was used to measure expression variation of 41 genes in lymphoblastoid cells of 40 unrelated individuals. For 25 genes found to be differentially expressed, additional analysis was performed in 10 CEPH families to determine heritabilities and map loci harboring regulatory variation. Seventy-six percent of the differentially expressed genes had significant heritabilities, and genomewide linkage analysis led to the identification of significant eQTLs for nine genes. Most eQTLs were in trans, with the best result (P=7.46×10−8) obtained for TMEM1 on chromosome 12q24.33. A cis-eQTL identified for CCT8 was validated by performing an association study in 60 individuals from the HapMap project. SNP rs965951 located within CCT8 was found to be significantly associated with its expression levels (P=2.5×10−5) confirming cis-regulatory variation. The results of our study provide a representative view of expression variation of chromosome 21 genes, identify loci involved in their regulation and suggest that genes, for which expression differences are significantly larger than 1.5-fold in control samples, are unlikely to be involved in DS-phenotypes present in all affected individuals.

Journal Article.  5583 words.  Illustrated.

Subjects: Genetics and Genomics

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