OPG has previously been shown to promote MMP release from monocytes and vascular smooth muscle cells,31,32 and aberrant aortic ECM (extracellular matrix) remodeling has been suggested to play a key role in the pathogenesis of AAA.33 However, we note that further studies are needed to validate our biomarker data. The gene discussed is TNFRSF11B; the disease is triple-A syndrome.