In immunohistochemistry, the prominent MMP-3/TIMP-1 and TIMP-2 imbalance (Figures 3a and 3b) with a persistent increase of MMP-cleaved aggrecan neoepitope (Figures 5a and 5b) was observed in the AF as well as in the NP. The gene discussed is ACAN; the disease is atrial fibrillation.