We investigated gene expression in markers with p<10−5 using the online database BioGPS (Wu et al., 2009), which includes expression information across 79 tissue types (Su et al., 2004). We also conducted secondary analyses of markers with p<10−3 to assess whether these markers were enriched for gene ontology categories, using the online database ToppGene (Chen et al., 2009). Of the 938 markers meeting the p<10−3 threshold, 538 are located within 366 known genes; gene ontology information was available for 321 of these through ToppGene. We employed a FDR of p<0.05 as the significance criterion, and excluded categories that applied to fewer than 3 genes. We note that this method does not take into account the fact that larger genes are likely to span more markers than small genes, and are thus more likely to harbor a marker meeting our p-value threshold by chance alone.
