Mutation of the WRN gene causes the accelerated aging condition Werner Syndrome. Absence of the correctly formed protein encoded by the gene impairs DNA repair, which in turn leads to the symptoms of accelerated aging. But as this research shows, gene expression of WRN appears to decline with "normal" aging as well: "The WRN gene encodes DNA helicase participating in genome maintenance. We looked for associations of natural aging with expression and methylation of this gene in blood mononuclear cells and with its common polymorphisms. Analyses were performed in ethnically homogenous Polish Caucasians. The mean level of the WRN messenger RNA was significantly lower in long-living individuals than in young and middle-aged controls. Analysis [showed] that aging might be accompanied by a slight increase of its methylation status; however, it seems to be biologically insignificant. Finally, analysis [showed] that the frequencies of the L1074F and C1367R polymorphisms were similar in all age groups tested ... We suggest that age-related decrease of the WRN expression but not its common genetic variants might contribute to human immunosenescence."