Disadvantaged environments affect genetic material

Children experiencing chronic stress from a disadvantaged life have shorter telomeres than their advantaged peers, according to a study led by Dr. Daniel Notterman, vice dean for research and graduate studies, and professor of pediatrics, and biochemistry and molecular biology, Penn State College of Medicine.

Telomeres are DNA sequences at the end of each chromosome that protect the ends of the chromosomes from damage. They vary in length per person and shrink as a person ages, a process that may be linked to health and disease.

The negative health effects of long-term chronic stress may be connected to the shortening of telomeres. Telomeres shorten faster in individuals experiencing chronic stress, such as that from living in a disadvantaged environment.

Notterman and colleagues studied genetic information from 40 9-year-old African-American boys.

Boys from disadvantaged environments had shorter telomeres than peers in the study who were not.  In addition, the effect of environment on telomere length was mediated by genes involved with the function of two neurotransmitters, dopamine and serotonin. Neurotransmitters help transmit signals between brain cells and send information throughout the body.

For boys with genetic variants of dopamine or serotonin pathways that conferred greater sensitivity to environmental signals associated with stress, those from disadvantaged environments had the shortest telomeres, and those from advantaged environments had the longest.

The results suggest a link between genetic factors and social environment associated with changing telomere length, and provide a biomarker for chronic stress exposure in children as young as 9, according to the authors.

Researchers also from Penn State College of Medicine are Arthur Berg, PhD, associate professor of biostatistics and bioinformatics and Sue Siegel, PhD, assistant professor of biochemistry and molecular biology.

The study is published in PNAS and was supported by the NIH-NICHD and the Penn State Clinical and Translational Science Institute. For more information, visit PNAS's Early Edition.

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