A new study suggests that is the same couple they are not genetically identical. A certified twin is two babies that come from the same fertilized egg.
Scientists in Iceland analyzed DNA from 387 pairs of identical couples, their parents, children, husbands or wives.
The tests made the team find “early changes That couple is unique, ”said lead researcher and geneticist Kari Stefansson. He is a professor at the University of Iceland and founded the company deCODE genetics.
Variables are small changes in DNA that can occur when a cell divides in an attempt to replicate itself. These small changes can affect a person’s physical appearance or control a person’s ability to fight disease.
The recently discovered mutations show that identical twins have genetic differences, the researchers said. The results were recently published in The genetics of nature.
On average, 5.2 of these early genetic differences have a pair of 5.2, the researchers found. But about 15 percent of the same couple pairs more than that. Some could be as much as 100 genetic differences, Stefansson said.
These differences represent a small fraction of the genetic material of each pair. But they could affect why one pair is higher or why one is at greater risk for some cancers than the other.
In the past, many researchers felt that physical differences seen in a similar pair were largely related to environmental influences, such as nutrition or lifestyle behavior.
Jan Dumanski is a geneticist at Uppsala University in Sweden. He was not involved in the investigation. He praised the findings as “clear and important donation”To medical research.
“The persuasion that we need to be very careful when using twins as a model ”to study the effects of genetics or the environment, Dumanski said.
Paper in 2008 submitted American Journal of Human Genetics find some genetic differences between identical twins. The new study, however, goes beyond earlier work by including the DNA of parents, children, husbands and wives of identical couples.
Examination of family members allowed the researchers to study when genetic mutations occurred in two cell types: those that were present in just one individual and those that were administered to the individual ‘s children.
Stefansson said his team found a twin where mutation is present in all cells of one pair ‘s body, but not in the other. However, “sometimes the second pair may show a mutation in some cells, but not all cells,” he said.
The researchers said they also found mutations that came before the developing embryo split in two.
Nancy Segal is a psychologist who studies twins at California State University, Fullerton. She was not involved in the investigation. But she called the results “heroic and real.” important. ”
Segal said the research tends to get more scientists to reconsider the genetic and environmental effects of twins. “Couples are very similar, but not at all,” she said.
My name is Bryan Lynn.
The Associated Press told this story. Bryan Lynn did the report for VOA Learning English. It was Mario Ritter, Jr. the editor.
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Words in this story
couple – n. either two babies born to the same mother at the same time
mutation – n. change in plant or animal genes
pair – n. two of the same
lifestyle – n. the way in which a person or group of people lives
donation – n. something that is added or given to a larger cause
persuasion – n. something that is suggested without being said directly
important –Adj. important