An example of the study of epigenetics starting to deliver targets for therapy: "scientists used human tissue samples to discover that those with osteoarthritis have a signature epigenetic change (DNA methylation) responsible for switching on and off a gene that produces a destructive enzyme called MMP13. This enzyme is known to play a role in the destruction of joint cartilage, making MMP13 and the epigenetic changes that lead to its increased levels, prime targets for osteoarthritis drug development. ... To make the discovery, [researchers] compared the extent to which DNA methylation was different in cartilage from patients suffering from osteoarthritis and healthy people of similar age. They found that at one small position, the gene for MMP13 had less DNA methylation in diseased patients. Then they confirmed that reduced methylation of this gene increases levels of the destructive enzyme MMP13. ... We've already seen how epigenetics has advanced our approach to cancer. Now we're seeing it with other diseases ... This study not only lays the groundwork for a new understanding of osteoarthritis, but also shows that the old 'either/or' nature v. nurture argument is outdated: epigenetics teaches us that nature (the daily wear and tear of joints) regulates nurture (the genes in our cartilage) to cause arthritis."