Scientists from Johns Hopkins University have found that long protective regions on DNA ends, which are thought to provide longevity, actually increase the risk of tumors. Research published New England Journal of Medicine.
Telomeres are regions at the ends of a chromosome that protect it from damage during cell division. Long telomeres in lab-grown cells have previously been shown to provide cellular longevity. A new study suggests that long-lived cells in humans may cause problems at the body level.
The study included 17 people from five families. All 17 people in the study had mutations in the POT1 gene. Normally POT1 inhibits telomere elongation, but its mutated form allows telomeres to be longer. All participants had an average of 90% longer telomeres than the general population, and nine had telomeres longer than 99% of people.
They were followed for several years and their medical histories were also analysed. Between the ages of 7 and 83, study participants suffered from an enlarged thyroid gland, various types of melanoma, lymphomas, other cancers, and uterine fibroids. Some participants had more than one of these conditions. Four patients who died during follow-up had lymphoma, colon cancer, leukemia, and brain tumor.
67% of elderly participants had hematopoietic-associated mutations, many more than commonly seen in older people. The increase in blood cell mutations may contribute to an increased risk of developing blood cancer, the researchers said.
However, six participants over the age of 70 showed some signs of long-lasting youth, such as the onset of gray hair later on.
“Our results challenge the idea that long telomeres protect against aging. Cells with very long telomeres seem to accumulate mutations and promote the development of tumors and other types of neoplasms that would otherwise be controlled by normal telomere shortening processes,” the scientists explained.