Schurmann, C.* ; Heim, K. ; Schillert, A.* ; Blankenberg, S.* ; Carstensen, M.* ; Dörr, M.* ; Endlich, K.* ; Felix, S.B.* ; Gieger, C. ; Grallert, H. ; Herder, C.* ; Hoffmann, W. ; Homuth, G.* ; Illig, T. ; Kruppa, J.* ; Meitinger, T. ; Müller, C.* ; Nauck, M.* ; Peters, A. ; Rettig, R.* ; Roden, M.* ; Strauch, K. ; Völker, U.* ; Völzke, H.* ; Wahl, S. ; Wallaschofski, H.* ; Wild, P.S.* ; Zeller, T.* ; Teumer, A.* ; Prokisch, H. ; Ziegler, A.*
     
 
    
        
Analyzing illumina gene expression microarray data from different tissues: Methodological aspects of data analysis in the MetaXpress consortium.
    
    
        
    
    
        
        PLoS ONE 7:e50938 (2012)
    
    
    
		
		
			
				Microarray profiling of gene expression is widely applied in molecular biology and functional genomics. Experimental and technical variations make meta-analysis of different studies challenging. In a total of 3358 samples, all from German population-based cohorts, we investigated the effect of data preprocessing and the variability due to sample processing in whole blood cell and blood monocyte gene expression data, measured on the Illumina HumanHT-12 v3 BeadChip array. Gene expression signal intensities were similar after applying the log(2) or the variance-stabilizing transformation. In all cohorts, the first principal component (PC) explained more than 95% of the total variation. Technical factors substantially influenced signal intensity values, especially the Illumina chip assignment (33-48% of the variance), the RNA amplification batch (12-24%), the RNA isolation batch (16%), and the sample storage time, in particular the time between blood donation and RNA isolation for the whole blood cell samples (2-3%), and the time between RNA isolation and amplification for the monocyte samples (2%). White blood cell composition parameters were the strongest biological factors influencing the expression signal intensities in the whole blood cell samples (3%), followed by sex (1-2%) in both sample types. Known single nucleotide polymorphisms (SNPs) were located in 38% of the analyzed probe sequences and 4% of them included common SNPs (minor allele frequency >5%). Out of the tested SNPs, 1.4% significantly modified the probe-specific expression signals (Bonferroni corrected p-value<0.05), but in almost half of these events the signal intensities were even increased despite the occurrence of the mismatch. Thus, the vast majority of SNPs within probes had no significant effect on hybridization efficiency. In summary, adjustment for a few selected technical factors greatly improved reliability of gene expression analyses. Such adjustments are particularly required for meta-analyses.
			
			
				
			
		 
		
			
				
					
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        Publikationstyp
        Artikel: Journalartikel
    
 
    
        Dokumenttyp
        Wissenschaftlicher Artikel
    
 
    
        Typ der Hochschulschrift
        
    
 
    
        Herausgeber
        
    
    
        Schlagwörter
        Breast-cancer ; Genome Browser ; Metaanalysis ; Profiles ; Population ; Signature ; Survival ; Risk ; Classification ; Information
    
 
    
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        Sprache
        englisch
    
 
    
        Veröffentlichungsjahr
        2012
    
 
    
        Prepublished im Jahr 
        
    
 
    
        HGF-Berichtsjahr
        2012
    
 
    
    
        ISSN (print) / ISBN
        1932-6203
    
 
    
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	    Band: 7,  
	    Heft: 12,  
	    Seiten: ,  
	    Artikelnummer: e50938 
	    Supplement: ,  
	
    
 
  
        
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            Verlag
            Public Library of Science (PLoS)
        
 
        
            Verlagsort
            Lawrence, Kan.
        
 
	
        
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        Begutachtungsstatus
        Peer reviewed
    
 
     
    
        POF Topic(s)
        30501 - Systemic Analysis of Genetic and Environmental Factors that Impact Health
30202 - Environmental Health
    
 
    
        Forschungsfeld(er)
        Genetics and Epidemiology
    
 
    
        PSP-Element(e)
        G-500700-001
G-504100-001
G-504200-002
G-504000-002
G-504200-003
    
 
    
        Förderungen
        
    
 
    
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        Erfassungsdatum
        2012-12-31