MADISON Genetic abnormalities are most often discussed in terms of differences so miniscule they are actually called "snips" changes in a single unit along the 3 billion that make up the entire string of human DNA.
"There's a whole world beyond SNPs single nucleotide polymorphisms and we've stepped into that world," says Brian Teague, a doctoral student in genetics at the University of Wisconsin-Madison. "There are much bigger changes in there."
Variation on the order of thousands to hundreds of thousands of DNA's smallest pieces large swaths varying in length or location or even showing up in reverse order appeared 4,205 times in a comparison of DNA from just four people, according to a study published May 31 in the Proceedings of the National Academy of Sciences.
Those structural differences popped into clear view through computer analysis of more than 500 linear feet of DNA molecules analyzed by the powerful genome mapping system developed over nearly two decades by David C. Schwartz, professor of chemistry and genetics at UW-Madison.
"We probably have the most comprehensive view of the human genome ever," Schwartz says. "And the variation we're seeing in the human genome is something we've known was there and important for many years, but we haven't been able to fully study it."
To get a better picture of those structural variations, Schwartz and his team developed the Optical Mapping System, a wholly new type of genome analysis that directly examines millions of individual DNA molecules.
Common systems for analyzing genomes typically chop long DNA molecules into fragments less than a couple thousand base pairs long and multiply them en masse, like a copy machine, to develop a chemical profile of each piece.
Reading such small sections without seeing their place in the larger picture of DNA leaves out critical understanding. To make matters worse, interesting parts of the human geno
|Contact: David C. Schwartz|
University of Wisconsin-Madison