Thursday, January 21, 2021

Genetic differences between monozygotic twins

Amazing stuff coming again out of tiny Iceland!

"Despite the important role that monozygotic twins have played in genetics research, little is known about their genomic differences. Here we show that monozygotic twins differ on average by 5.2 early developmental mutations and that approximately 15% of monozygotic twins have a substantial number of these early developmental mutations specific to one of them. ..."

"... Rather than having exactly the same DNA sequences, twins start accumulating genetic variation from the earliest stages of development, researchers at Iceland-based company deCODE genetics [founded in 1996] found, meaning that one twin harbors variants that aren’t present in the other. ...
The new study focuses specifically on mutations that occur as or before embryos form from the mass of cells inside the blastocyst, a structure that implants in the uterine wall. During this stage of development, this inner cell mass can split to form two separately developing embryos.
Drawing on deCODE’s genetic databases to analyze variation in multiple cells sampled from 381 monozygotic twin pairs and their immediate family members, the researchers pinpointed a number of mutations that arose during this stage of development in just one member of each pair, meaning that at birth, so-called identical twins may already differ genetically from each other.
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Differences between germline genomes of monozygotic twins | Nature Genetics

Identical Twins Accumulate Genetic Differences in the Womb (contains interview with CEO of deCode genetics)

Kári Stefánsson, CEO


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