Figure 4 .

Average linkage analysis of 1185 transcripts from all 10 samples as assayed by microarray. The left column (A) displays all 10 assayed samples with 1185 genes placed in rows. Each gene is represented by a single row of coloured boxes with correlation between level of expression and intensity of colour ranging from black (no expression) to bright red (high expression). The yellow lines in column A frame one identified homogeneous cluster of genes highly expressed in all three SpA samples. Column B is a magnified segment of the left column showing 16 genes within that particular cluster. Nine of the 16 genes, underlined in red, were also identified by t test in either SpA v OA or SpA v HC, and five of nine genes within that cluster were found to be among the genes expressed significantly in both the t test comparison groups.