According to the analysis, sisters of centenarians had about one-half the risk of dying at any given age compared to the national average. Brothers of centenarians had similarly low mortality rates, except during the teenage years and young adulthood. [...] University of Utah researchers found brothers, sisters and other first-degree relatives of the long-lived tend to live longer lives than cousins and other more distant relatives, suggesting that a small number of genes might influence exceptional longevity. In 2001, Dr. Perls and his colleagues found a region on chromosome 4 that is "highly suggestive" of genetic predisposition to exceptional longevity.