In a large genetic study, they found that many people have stretches of DNA that gradually expand with age. Common genetic variants can greatly affect the rate of this expansion, up to about fourfold. Researchers have identified specific stretches of DNA that are associated with severe kidney disease. In addition, they also found enlargements associated with severe liver disease. The findings show that such age-related DNA instability is very common in humans. The study thus points out that differences in genetic make-up can significantly determine how unstable an individual's DNA is during life.