Detection of DNA mosaic structure

Current science suggests that all cells in the body contain identical DNA. However, a new study of skin stem cells has found that genetic variation is widespread in the body's tissues. According to Yale Medical School researchers, this is a finding that has profound implications for genetic screening.

Published in the November 18 issue of Nature, this study paves the way to assessing the level of genetic modification, and helps to better understand human development and disease.

"We found that humans are made up of a mosaic structure of cells with different genomes," said Dr. Flora Vaccarino, Professor Harris of child psychiatry at the Children's Research Center. Yale said, "We see 30% of the copy variable variation (CNV - copy number variations), that is, the DNA fragments will be deleted, duplicated. Previously it was assumed that these variations only occurred in the case of the disease, as the mosaic cancer we saw on the skin could also be found in the blood, in the brain, and other parts of the muscle. human being ".

We have the belief that our cells have the same DNA sequence. However, the Yale University team challenged this.

Some scientists have hypothesized that during development, when DNA is copied from the mother to the daughter cell, it could be deleting, copying and changes in DNA sequences, and a whole group. The gene may be affected. It is difficult to test this hypothesis, but in the new study, Vaccarino and colleagues have done that.

The team used the entire genome sequence to study induced pluripotent stem cells (iPS), which are stem cells developed from a different adult cell. The team developed cells from the skin cells of the two families. The researchers spent two years describing iPS cell lines and comparing them to the original skin cells.

While observing that the iPS cell genome is similar to the skin cell genome that is the source of these iPS cells, the team can determine some deletion or row-related copying. thousand base pairs of DNA. Later, the team performed additional experiments to understand the origin of those differences, and showed that at least half of them existed first in tiny parts of skin cells. These differences have been revealed in iPS cells because each iPS line is derived from one, or very few, skin cells. Vaccarino says iPS lines can act as a magnifying glass to see pictures of genetic differences in the body's cells.

"These findings are shaping our future studies, and we are continuing to work to see if this phenomenon exists in the developing human and animal brains ," Vaccarino added. .

Vaccarino works with a team of researchers from several other laboratories. This study is funded by NIH / NIMH, Simons Foundation and Connecticut State.