Some diseases are hereditary that are passed on to next generation. If a person is suffering from diseases like Alzheimer’s or diabetes then it is very likely that his next generation will suffer from the same disease. Heredity is all due to genes and some high-risk gene variants persist from generation to generation. In a new study, scientists have decoded that why such high-risk gene do not get out by natural selection during evolution.
Researchers explained that the same process which helps us in protecting against pathogens, also help the occurrence of mutations in our genome that predispose us to hereditary diseases.
Balancing selection is the process of exclusion of harmful genes through natural selection during evolution. To confirm why some harmful genes stay in our body instead of getting eliminated automatically, a team of researchers from the Max Planck Institute for Evolutionary Biology in Plon, Germany and the Harvard Medical School conducted genetic analysis of 6,500 people and found that balancing selection that increases the diversity of immune proteins also affects neighbouring DNA segments.
Scientists were skeptical if balancing selection is leading to conservation of harmful gene variants. Study authors then conducted computer simulations to confirm it.
“I did expect that higher resistance to pathogens might lead to an accumulation of some harmful mutations. But the extent to which such mutations persist in the population really surprised me,” Tobias Lenz from Max Planck Institute in Plon. “It would be interesting to know how many genetic diseases in humans can be traced back to contact with pathogens we have encountered in the course of our evolution,” Lenz noted.
Since human genes have evolved continuously to adapt new pathogens, it has resulted in the diversity of our immune genes. Scientists say that diversity protects us from pathogens but it also extends to neighboring DNA segments and protects some harmful gene variants. It is the price we pay for the genetic diversity which is essential for our survival.
The study appeared in the journal Molecular Biology and Evolution.