Home Sciences A change in DNA made humans more susceptible to cancer

A change in DNA made humans more susceptible to cancer

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When the human being separated at an evolutionary level from the rest of the primates, a subtle modification in a gene caused him to acquire greater possibilities of contracting some type of cancer. The change in the BRCA2 gene triggers a 20 percent reduction in DNA repair ability.

A team of researchers from the Sloan Kettering Institute in the United States has discovered evidence of a change in human DNA after differentiating from other primates that has made our species more susceptible to development of cancerous tumors. The key is a small difference in the BRCA2 gene, which must have arisen after humans diverged from other primates.

In general, the primates they are an order of placental mammals that includes humans and their closest relatives, such as chimpanzees (with whom we share 98.7 percent of our DNA) or bonobos. Primates arose on Earth between fifty-five and eighty-five million years ago, from the evolution of small land mammals. According to the study of the genome of humans and chimpanzees, both species would have separated evolutionarily approximately 4.1 million years ago.

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Although this separation was what led to the development of the characteristics that make us human, such as the capacities inherent in the cerebral cortex, it would also have led to a genetic modification that, in principle, could go unnoticed: a slight variation in the BRCA2 gene. This gene, responsible for encoding the protein of the same name, has been identified in most mammals for which the complete genome is available.

Reduced DNA repair ability

According to an article published on Phys.org, after performing a comparative analysis in human and non-human primates To identify sequence variations in cancer-related genes, scientists led by Christine Iacobuzio-Donahue managed to discover 395 human-specific substitutions that arose during evolution and separation from the rest of the primates. At the same time, using bioinformatic analyses, they were able to determine the functional consequences of these substitutions: they appear to alter the function of the protein linked to the BRCA2 gene.

Said alteration decreases the effectiveness of BRCA2 in DNA repair coding by about 20 percent: According to the researchers, this could explain why humans are more susceptible to the development of cancerous tumors than other primates. It is that the decrease in DNA repair leads to a reduction in the antitumor potential of BRCA2.

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Compensation through an increase in reproductive capacity?

Why did that occur? genetic modification during human evolution? For the specialists, there must have been some kind of “compensation” in terms of improvement in reproductive capacity. In this direction, previous studies have confirmed that women with a higher probability of developing ovarian and breast cancer, two tumors directly related to the activity of the BRCA2 gene, can get pregnant more easily.

Finally, the work of American scientists suggests that a possible treatment for cancer in the distant future may involve the BRCA2 gene alterationwith the purpose of achieving a behavior similar to that observed in other primates, thus reducing the risk of developing cancer.

Reference

Evidence for Reduced BRCA2 Functional Activity in Homo Sapiens After Divergence from the Chimpanzee-Human Last Common Ancestor. Christine A. Iacobuzio-Donahue et al. Cell Reports (2022). DOI:https://doi.org/10.1016/j.celrep.2022.110771

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