Mutations may also lead to the truncation (shortening) of the WRNp protein, leading to the loss of its nuclear localization signal sequence, thus it is no longer transported into the nucleus where it interacts with the DNA. This leads to a reduction in DNA repair. Furthermore, mutated proteins are more likely to be degraded than normal WRNp. Apart from causing defects in DNA repair, its aberrant association with p53 down-regulates the function of p53, leading to a reduction in p53-dependent apoptosis and increasing the survival of these dysfunctional cells. Cells of affected individuals also have reduced lifespan in culture, have more chromosome breaks and translocations and have extensive deletions.Patients with Werner syndrome lose the RecQ helicase activity in the WRN protein because of the loss of its C-terminus region, but the mechanism by which this happens is unclear. The loss of the helicase activity can have far-reaching consequences in terms of cell stability and mutation. One instance of these consequences involves telomeres. It is thought that the WRN helicase activity is important not only for DNA repair and recombination, but also for maintaining telomere length and stability. Thus, WRN helicase is important for preventing catastrophic telomere loss during DNA replication. In a normal cell, the telomeres (the ends of chromosomes) undergo repeated shortening during the cell cycle, which can prevent the cell from dividing and multiplying.
Between 1934 and 1941, two internists from New York, Oppenheimer and Kugel, coined the term "Werner Syndrome," igniting a wave of interest and research on the disease. During that time, Agatson and Gartner suggested a possible link between Werners syndrome and cancer. However, it was not until 1966 that there was a general consensus on the autosomal recessive mode of inheritance for the syndrome. By 1981, geneticists had located the WRN gene on chromosome 8, leading to its cloning in 1996. This cloning of the WRN was significant because it revealed the predicted WRN protein was made from a family of DNA helicases. Prior to 1996, Werner syndrome was thought to be a model for accelerated aging. Since the discovery of the gene, it has become clear that the premature aging displayed in Werner syndrome is not the same, on a cellular level, as normal aging. The role of WRN in DNA repair and its exonuclease and helicase activities have been the subject of many studies in recent years.Since the initial discovery in 1904, several other cases of Werner syndrome have been recorded. Many of these cases have occurred in Japan, where a founder effect has caused a higher incidence rate than in other populations. The incidence rate of Werner syndrome in Japan is approximately 1 case per 100 thousand people (1:100,000), a large contrast with the rate of incidence for the rest of the world, which is between 1:1,000,000 and 1:10,000,000.