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  • 10 January, 2021

  • 10 Min Read

Identical twins are not exactly genetically the same

Identical twins are not exactly genetically the same

  • 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.
  • 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.
  • 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.
  • 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.

Source: TH

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