The effects of age and lifestyle factors on the accumulation of cytogenetic damage as measured by chromosome painting

Our plain-English summary of The effects of age and lifestyle factors on the accumulation of cytogenetic damage as measured by chromosome painting, by M.J. Ramsey, D.H. Moore, J.F. Briner, et al (Mutation Research, 1995).

The study

• Authors: M.J. Ramsey, D.H. Moore, J.F. Briner, D.A. Lee, L.A. Olsen, J.R. Senft, J.D. Tucker
• Journal: Mutation Research
• Published: 1995;338(1-6):95-106
• Cited by: 245 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Individual responses to the aging process are variable and are affected by genetic as well as environmental factors. Fluorescent in situ hybridization with whole chromosome probes ('chromosome painting') provides an efficient approach for detecting structural chromosome aberrations in human lymphocytes. This rapid and sensitive technique is an effective tool for quantifying chronic exposure to environmental agents which may result in an accumulation of cytogenetic damage with age. We have applied this technology to a normal, putatively unexposed, population to document the relationship between age and the accumulation of cytogenetic damage, as well as to establish a baseline frequency of stable aberrations. Using probes for chromosomes 1, 2 and 4 simultaneously, the equivalent of 1000 metaphases was scored for stable and unstable aberrations from each of 91 subjects ranging in age from newborns (umbilical cord bloods; n = 14) to adults aged 19 to 79 years. Each subject (or one parent of each newborn) completed an extensive questionnaire to identify possible lifestyle factors that may influence the frequency of cytogenetic damage. Our findings show a significant increase in stable aberrations (translocations and insertions) with age (p < 0.0001). We also observed age-related increases with dicentrics (p < 0.0001) and acentric fragments (p < 0.0001). Relative to the frequencies observed in cord bloods, the frequencies of stable aberrations, dicentrics, and acentric fragments in adults aged 50 and over were elevated 10.6-fold, 3.3-fold, and 2.9-fold, respectively. Nine variables other than age are significantly associated with the frequency of stable aberrations; these are: smoking (two variables), consumption of diet drinks and/or diet sweeteners (4 variables), exposure to asbestos or coal products (1 variable each), and having a previous major illness (1 variable). Newborns whose mothers smoked during pregnancy had a 1.5-fold increase in stable aberrations (p = 0.029). Repeat samples from a subset of the adults indicate that for most subjects there is little change in individual translocation frequencies over a period of two to three years. These results support the hypothesis that stable chromosome aberrations show a greater accumulation with age than do unstable aberrations and suggest that lifestyle factors contribute to the accumulation of cytogenetic damage.

In plain English

This study looked for chromosome damage in white blood cells (lymphocytes) from 91 healthy people the authors described as putatively unexposed. There were 14 newborns, sampled from umbilical cord blood, and adults aged 19 to 79 who were employees, retirees or spouses of retirees of the Lawrence Livermore National Laboratory. Using a staining method called chromosome painting, the authors counted lasting (stable) and short-lived (unstable) chromosome changes. They compared these counts with age and with answers to a lifestyle questionnaire. Age alone accounted for 70.0% of the variation in stable changes. In adults aged 50 and over, stable changes were 10.6-fold higher than in cord blood. Of 54 factors tested, nine were each associated with more stable changes. These were asbestos exposure, coal products, smoking, diet drinks or sweeteners, and a previous major illness. Asbestos exposure was a single questionnaire variable; the article gives no fiber type or amount. The authors cautioned that, apart from age, these factors could be spuriously significant and should be confirmed in a separate study. Babies of mothers who smoked during pregnancy had more stable changes (p = 0.029).

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Study of chromosome aberrations in blood lymphocytes measured by chromosome painting, with questionnaire factors tested one at a time against aberration frequency (age forced in as a covariate); repeat blood samples from 20 adults two to three years later
• Who was studied: 91 healthy people aged newborn to 79 years: 14 umbilical cord blood samples from full-term healthy babies, and adults aged 19 to 79 who were employees, retirees, or spouses of retirees of the Lawrence Livermore National Laboratory (California, USA)
• Exposure: Age and lifestyle factors from a questionnaire (54 factors). These included tobacco use, diet, diet drinks and sweeteners, alcohol, medical history, and exposures such as asbestos, coal products, radiation, pesticides and solvents. Asbestos exposure was one variable; no fiber type, product, job or dose is given.
• Main results:
  • In the whole group, age alone accounted for 70.0% of the variation in stable aberration frequencies (p < 0.0001)
  • In adults aged 50 and over (37 subjects), compared with cord bloods, stable aberrations were elevated 10.6-fold, dicentrics 3.3-fold and acentric fragments 2.9-fold
  • Nine variables other than age were statistically significant (p < 0.05), and each was associated with an increase in stable aberrations. These were smoking (two variables), diet sweeteners and/or diet drinks (four variables), exposure to asbestos (one variable), exposure to coal products (one variable), and previous major illness (one variable).
  • The probability of finding nine significant variables out of 54 tests by chance was 0.0013 if the variables were independent. After the authors adjusted for related pairs (6 out of 51), it was 0.041.
  • Six babies whose mothers smoked during pregnancy had significantly higher stable aberration frequencies than eight babies whose mothers did not (p = 0.029)
  • Among 20 adults resampled two to three years later, most showed no substantial change in stable aberration frequency. Three of the four with the highest frequencies showed a significant decline.
• The authors' conclusion: The authors concluded that stable chromosome damage accumulates with age at a significantly higher rate than unstable damage. They reported associations with several lifestyle factors, including asbestos exposure. They stated that whether these associations will be confirmed in an independent study remains to be determined.
• Limitations the authors state:
  • Apart from age, the significant variables (including asbestos exposure) could be spuriously significant and should be confirmed in a separate, independent study population
  • Chromosome painting with the probes used detects only a fraction of all chromosome exchanges; the authors compensated by scoring more cells
  • The 20 adults resampled were not chosen at random; they were selected because their stable aberration frequencies were high or low for their age group

Topics

Medical terms in this study, explained in our Lexicon: Translocation.

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