Although rat exon array demonstrated a significant upregulation of 51 genes when comparing G2 to G1, alpha-2-macroglobulin gene was particularly found to be overexpressed when comparing steroid-treated Wistar Kyoto rats which had developed ANFH (G2) to placebo rats (G1) (FC = 3.52, P = 0.0005). Here, A2M is linked to familial avascular necrosis of femoral head.