We also inspected the categories of genes identified by the most relaxed threshold for SNPs (i.e., <0.05). A total of 72 and 85 categories were significant for OZALC-NAG and SAGE respectively (category-specific p-value <0.01) (Table 2). Eleven GO terms and one KEGG pathway were common to both studies. These terms and pathways showed an overlap among the constituent genes; thus we grouped these into 4 clusters of categories of genes that reflected the similarity of the genes included (Table 3; Figure S1). These clusters were labeled i) cholinergic nicotinic receptors, ii) sensory perception of chemical stimulus/smell related genes, iii) ribosome genes, and iv) retinoid binding genes. Eight of these categories of genes were significant in ARIC (category-specific p-value<0.05). Neither of the two retinoid binding GO terms showed statistical significance for the ARIC study. In contrast, each of the remaining 3 clusters included at least one GO term with category-specific p-values lower than 0.01 for the ARIC study.
