26 March 2011Light on genetic dark matter Science News 179(7):30.
"Genetic dark matter" (SN: 12/18/10, p. 18) might be hiding in plain sight. For over two decades, abundant variation in the number of tandemly repeated units in microsatellite and minisatellite DNA has been used for genetic fingerprinting. For years, this variation has been widely regarded as functionally meaningless. For much of that time, several biologists (including myself) have hypothesized that such repeat-number variation might help account for heritable variation in certain traits.
Most such repeats are indeed found in genomic regions that lack known function. But among the hundreds of thousands of repeats scattered throughout the human genome are many that are closely associated with genes. Lots of genes, perhaps most, include at least one variable tandem repeat sequence at sites where the number of repeat units can influence gene function. Nevertheless, most attention (and most research investment) remains focused on single nucleotide polymorphisms (SNPs) for the very simple reason that collecting vast data sets on SNPs has become cheap and easy. Although surveying repeat number variation and linking this variation with phenotypic differences are technically challenging, biologists should not lose sight of this very visible source of heritable variation.
Science News has covered some of the relevant studies in past articles (SN: 12/18/04, p. 387; SN: 1/31/09, p. 26). The subject of repeat number variation might be suitable for an article that could shed light on many inter-related topics - triplet repeat diseases, evolutionary facilitation, molecular genetics, genomic diversity, etc.
G. King, Carbondale, Ill.
SN: 1/31/09, p.
Fondon III, J.W., E.A.D. Hammock, A.J. Hannan, and D.G. King (2008) Simple sequence repeats: Genetic modulators of brain function and behavior. Trends in Neurosciences 31: 328-334. doi: 10.1016/j.tins.2008.03.006. [authors' prepublication MSWord document]
Y. Kashi and D.G. King (2006) Simple Sequence Repeats as Advantageous Mutators in Evolution. Trends in Genetics 22: 253-259. [Abstract] doi: 10.1016/j.tig.2006.03.005
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