Identical twins aren't perfect clones, research shows | iNFOnews | Thompson-Okanagan's News Source

Current Conditions

Smoke
29.3°C

Kamloops News

Identical twins aren't perfect clones, research shows

FILE - In this Saturday, June 18, 2005 file photo, identical twins Alf, left, and Sven Fehnhanhn, left background, 79, from Kassel, pose along with seven-month-old Luis Carl, right, und Albert Frank Millgramm, right background, during a twins' meeting in Berlin. According to research published on Thursday, Jan. 7, 2021, identical twins are not exactly genetically the same.
Image Credit: (AP Photo/Jockel Finck)
January 08, 2021 - 5:30 AM

WASHINGTON - If you’re an identical twin who’s always resisted being called a clone of your sibling, scientists say you have a point.

Identical twins are not exactly genetically the same, new research shows.

Scientists in Iceland sequenced DNA from 387 pairs of identical twins — those derived from a single fertilized egg — as well as from their parents, children and spouses. That allowed them to find "early mutations that separate identical twins,” said Kari Stefansson, a geneticist at the University of Iceland and the company deCODE genetics, and co-author of the paper published Thursday in the journal Nature Genetics.

A mutation means an alteration in a sequence of DNA — a tiny change that is not inherently good or bad, but can influence physical features or susceptibility to certain diseases. They can occur when a cell divides and makes a slight error in replicating DNA.

On average, identical twins have 5.2 of these early genetic differences, the researchers found. But about 15% of identical twin pairs have more genetic differences, some of them up to 100, said Stefansson.

These differences represent a tiny portion of each twin’s genetic code, but they could influence why one twin is taller or why one twin is at greater risk for certain cancers.

Previously, many researchers believed that physical differences between identical twins were related mostly to environmental factors, such as nutrition or lifestyle.

Jan Dumanski, a geneticist at Uppsala University in Sweden, who was not involved in the new paper, praised it as “a clear and important contribution” to medical research.

“The implication is that we have to be very careful when we are using twins as a model" for teasing apart the influences of nature and nurture, he said.

Previous studies, including a 2008 paper in The American Journal of Human Genetics, have identified some genetic differences between identical twins.

The new study goes beyond earlier work by including DNA of parents, children and spouses of identical twins. That allowed the researchers to pinpoint when genetic mutations occurred in two different kinds of cells — those present in just one individual and those inherited by that person’s children. They also found mutations that occurred before the developing embryo split into two, setting the stage for twins.

Stefansson said that his team had found pairs of twins where a mutation is present in all cells of the body of one twin, but not found in the other twin at all. However, “sometimes the second twin may show the mutation in some cells, but not all cells,” he said.

Nancy Segal, a psychologist who studies twins at California State University, Fullerton and was not involved in the paper, called the research “heroic and really significant.”

“This will force scientists to refine our thinking about the influences of genetics and environment,” she said. “Twins are very alike, but it is not a perfect similarity.”

___

The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Department of Science Education. The AP is solely responsible for all content.

News from © The Associated Press, 2021
The Associated Press

  • Popular kamloops News
  • Okanagan Lake nearing its lowest level in at least 20 years
    Okanagan Lake is now only about one centimetre higher than it was at this time in 2003 – which was one of the driest years on record. As of July 26, it sat at 341.87 metres above sea l
  • Kamloops woman comes face-to-face with thief in her home
    When Bev Rogers came home from a night shift at the hospital and found a bike mysteriously laying on her front yard on Kamloops' North Shore on Wednesday morning, she was surprised. What was m
  • Kelowna highrise sells out within 48 hours of going on sale
    The first of three residential highrise towers in the Water Street by the Park development in downtown Kelowna sold out almost as soon as they came on the market. The sales started on Friday
  • Young woman fends off attacker in Kamloops
    Kamloops RCMP responded to a North Shore volleyball court after hearing a young woman scream. On July 28, around 10:20 p.m., police found the youth uninjured after she fought off an attacker
  • Foreign student drowns in Shuswap lake
    A 27-year-old foreign exchange student has drowned in the Shuswap's White Lake. On July 28, the Salmon Arm RCMP, White Lake Fire Department and Shuswap Search and Rescue responded to a r
View Site in: Desktop | Mobile