Consensus in the scientific community told us that every cell in our body has a copy of our unique genetic code. It is an interesting proposal but practically impossible to verify with current technology until now. There has been advances in sequencing technology taking place which make it possible to check this assumption.
Researchers studying induced pluripotent stem cells (iPSC’s) (adult stem cells reprogrammed back to embyro stem cells used for medical treatments) have discovered copy number variations (CNV) in cells derived from skin cells. Most assumed these changes occurred in the process of inducing them to the pluripotent state but Yale researchers checking to see whether CNV’s are also found in the somatic cells from which the iPSC’s were derived.
Their paper published in nature says…
“Using PCR and digital droplet PCR, we show that at least 50% of those CNVs are present as low-frequency somatic genomic variants in parental fibroblasts (that is, the fibroblasts from which each corresponding human iPSC line is derived), and are manifested in iPSC lines owing to their clonal origin. Hence, reprogramming does not necessarily lead to de novo CNVs in iPSCs, because most of the line-manifested CNVs reflect somatic mosaicism in the human skin….”
“Overall, we estimate that approximately 30% of the fibroblast cells have somatic CNVs in their genomes, suggesting widespread somatic mosaicism in the human body. Our study paves the way to understanding the fundamental question of the extent to which cells of the human body normally acquire structural alterations in their DNA post-zygotically.”
What do they mean by “Somatic mosaicism?“ It’s basically jargon telling you that genomes differ from cell to cell! But not only in copy number variations (CNV’s), but they discovered it in single nucleotide polymorphisms (SNP’s) also. The long held assumption about you having only one genome is thus falsified. This discovery is telling us we have numerous genomes!
How is this going to affect genetics and evolutionary studies? Ever since the Human Genome Project published its epochal map of “the human genome,” there have been maps of other animals including chimps. But from what we know now about genome variations do those maps reflect reality in nature and are these maps depended upon which somatic cell was sequenced?
Geneticists have been aware of variations between individuals of a species which is why various ethic groups have been included in studies but this new discovery is finding significant variation within an individual’s own cells! It is not known at this time on how significant these changes are considering their study was based only on skin cells. But it is quite possible this could be a game changer…
“The 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 School of Medicine researchers.”
As far as the story of evolution, it has been claimed for years about small differences between human and chimpanzee genomes. What if the percent difference is a function of the source cells used? If there is a difference then that means any conclusions about human-chimp similarities would prove unreliable. Which cells should be averaged? Will the averages converge or diverge, depending on which cells are selected? Philosophers of science can have fun with this one!
Creationists have taken some of the claims about evolutionary similarities and differences based on genetics with a grain of salt and now this belief has been confirmed by this scientific study! This is going to be one of the more interesting areas in science!