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 School of Medicine researchers.
Published in the Nov. 18 issue of Nature, the study paves the way for assessing the extent of gene variation, and for better understanding human development and disease.
"We found that humans are made up of a mosaic of cells with different genomes," said lead author Flora Vaccarino, M.D., the Harris Professor of Child Psychiatry at the Yale Child Study Center. "We saw that 30 percent 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."
The longstanding belief has been that our cells have the same DNA sequence and this blueprint governs the body's functions. The Yale team's research challenges this dogma. Some scientists have hypothesized that during development, when DNA is copied from mother to daughter cells, there could be deletions, duplications and changes in the sequence of the DNA, and an entire group of genes could be affected. This premise has been incredibly difficult to test, but Vaccarino and colleagues have done so in this new study.
The team used whole genome sequencing to study induced pluripotent stem cells lines (iPS), which are stem cells developed from a mature-differentiated cell. The team grew cells taken from the inner upper arms of two families. The team spent two years characterizing these iPS cell lines and comparing them to the original skin cells.
While observing that the genome of iPS cells closely resembles the genome of skin cells from which they originated, the team could identify several deletions or duplications involving thousands of base pairs of DNA. The team then performed additional experiments to understand the origin of those differences, and showed that at least half of them pre-existed in small fractions of skin cells. These differences were revealed in iPS cells because each iPS line is derived from one, or very few, skin cells. Vaccarino said these iPS lines could act as a magnifying glass to see the mosaic of genomic differences in the body's cells.
"In the skin, this mosaicism is extensive and at least 30 percent of skin cells harbor different deletion or duplication of DNA, each found in a small percentage of cells," said 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."
"These findings are shaping our future studies, and we're doing more studies of the developing brains of animals and humans to see if this variation exists there as well," Vaccarino added.
Vaccarino worked with a team of researchers from several laboratories, including those of Mark Gerstein, Sherman Weissman, Alexander Eckehart Urban, working together under the auspices of the Program in Neurodevelopment and Regeneration. Other authors on the study include Alexej Abyzov, Jessica Mariani, Dean Palejev, Ying Zhang, Michael Seamus Haney, Livia Tomasini, Anthony Ferrandino, Lior A. Rosenberg Belmaker, Anna Szekely, Michael Wilson, Arif Kocabas, Nathaniel E. Calixto, Elena L. Grigorenko, Anita Huttner, and Katarzyna Chawarska.
The study was funded by NIH/NIMH, the Simons Foundation, and the State of Connecticut.
Citation: Nature doi:10.1038/nature11629
Karen N. Peart | EurekAlert!
Perseus translates proteomics data
27.07.2016 | Max-Planck-Institut für Biochemie
Severity of enzyme deficiency central to favism
26.07.2016 | Universität Zürich
Transparent electronics devices are present in today’s thin film displays, solar cells, and touchscreens. The future will bring flexible versions of such devices. Their production requires printable materials that are transparent and remain highly conductive even when deformed. Researchers at INM – Leibniz Institute for New Materials have combined a new self-assembling nano ink with an imprint process to create flexible conductive grids with a resolution below one micrometer.
To print the grids, an ink of gold nanowires is applied to a substrate. A structured stamp is pressed on the substrate and forces the ink into a pattern. “The...
A new Fraunhofer MEVIS method conveys medical interrelationships quickly and intuitively with innovative visualization technology
On the monitor, a brain spins slowly and can be examined from every angle. Suddenly, some sections start glowing, first on the side and then the entire back of...
Researchers at the U.S. Department of Energy's (DOE) Ames Laboratory have discovered an unusual property of purple bronze that may point to new ways to achieve high temperature superconductivity.
While studying purple bronze, a molybdenum oxide, researchers discovered an unconventional charge density wave on its surface.
Munich Physicists have developed a novel electron microscope that can visualize electromagnetic fields oscillating at frequencies of billions of cycles per second.
Temporally varying electromagnetic fields are the driving force behind the whole of electronics. Their polarities can change at mind-bogglingly fast rates, and...
Breakup of continents with two speed: Continents initially stretch very slowly along the future splitting zone, but then move apart very quickly before the onset of rupture. The final speed can be up to 20 times faster than in the first, slow extension phase.phases
Present-day continents were shaped hundreds of millions of years ago as the supercontinent Pangaea broke apart. Derived from Pangaea’s main fragments Gondwana...
15.07.2016 | Event News
15.07.2016 | Event News
11.07.2016 | Event News
27.07.2016 | Earth Sciences
27.07.2016 | Materials Sciences
27.07.2016 | Earth Sciences