Skin cell reveal DNA's genetic mosaic

Mon, 11/19/2012 - 1:25pm

iPS cells stained for proteins expressed during the cell cycle. Image: Vaccarino laboratoryThe prevailing wisdom has been that every cell in the body contains identical DNA. However, a new study of stem cells derived from the skin has found that genetic variations are widespread in the body's tissues, a finding with profound implications for genetic screening, according to Yale University School of Medicine researchers.


"We found that humans are made up of a mosaic of cells with different genomes," says lead author Flora Vaccarino, the Harris Professor of Child Psychiatry at the Yale Child Study Center. "We saw that 30% of skin cells harbor copy number variations (CNV), which are segments of DNA that are deleted or duplicated. Previously it was assumed that these variations only occurred in cases of disease, such as cancer. The mosaic that we've seen in the skin could also be found in the blood, in the brain, and in other parts of the human body."




"In the skin, this mosaicism is extensive and at least 30% of skin cells harbor different deletion or duplication of DNA, each found in a small percentage of cells," says Vaccarino. "The observation of somatic mosaicism has far-reaching consequences for genetic analyses, which currently use only blood samples. When we look at the blood DNA, it’s not exactly reflecting the DNA of other tissues such as the brain. There could be mutations that we're missing."


Source: Yale University


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