11 September 2015

Smoking is not dangerous for everyone

There is a large amount of evidence in favor of the fact that smoking seriously affects life expectancy and contributes to the progression of various diseases. It has also been suggested that exposure to tobacco smoke may have an impact on the risk of premature death and the development of diseases by accelerating the aging process. However, not all smokers are characterized by early mortality, and some of them manage to live even to very old age.

Taking the genotypes of long-lived smokers (a total of 90 people) as a material for the study and comparing them with the genotypes of smokers aged 52-69 years (a total of 730 people), scientists from the University of California at Los Angeles identified a complex of 215 single nucleotide polymorphisms, or "snips" (from the English SNP, single-nucleotide polymorphism), ensuring the ability of certain people to better tolerate the harmful effects of environmental factors (including smoking) and mitigating the manifestations of diseases.

When using an independent validation sample, which included 6,447 non–smokers, it was found that the identified complex of genetic variants increases the probability of reaching the age of 90-99 years by 22% and the centenary by more than three times. Moreover, it reduces the risk of developing cancer by almost 11%.

According to the authors, the complex of genetic markers identified by them not only demonstrates a pronounced correlation with a long life expectancy and a high survival rate. In addition, many of the markers included in it are related to signaling mechanisms known for their involvement in aging processes, and mechanisms that ensure the longevity of animal models. There is evidence indicating that the identified genetic variants can contribute to an increase in life expectancy by increasing the effectiveness of mechanisms for maintaining cell activity and repairing damage. This ensures the ability of some people's organisms to cope better with damage even under the conditions of active exposure to biological stressors, including those contained in tobacco smoke.

In general, the results obtained by the authors indicate that longevity is determined not only by the influence of environmental factors. It is regulated by complex genetic systems that form stress resistance and genome stability.

The article by Morgan E. Levine and Eileen M. Crimmins A Genetic Network Associated With Stress Resistance, Longevity, and Cancer in Humans is published in The Journals of Gerontology, Series A: Biological Sciences & Medical Sciences.

Evgenia Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru

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