First complete look at families’ genes
Genome sequences of parents and children pinpoint disease-causing mutations
Gene sequencing has become a family affair. Two independent teams of researchers have found DNA changes underlying rare diseases by comparing the complete genetic material of parents and one or more of their children.
The studies, appearing online March 10 in the New England Journal of Medicine and March 11 in Science, highlight how powerful family sequencing techniques can be for understanding genetic diseases, comments geneticist Stacey Gabriel of the Broad Institute, a joint research center of MIT and Harvard University. “It’s great to see rare disease genes being identified by sequence-based approaches,” she says. In these early days of using gene sequencing as a discovery tool, “family-based studies are a really interesting place to start.”
Reading all of the 3 billion base pairs in the human genome and identifying the differences between people is daunting. Sequencing techniques can misread some of the base pairs, calling a particular base an A instead of a G, for example. Such reading errors occur roughly 1,000 times more frequently than the expected mutation rate, says Science study coauthor David Galas of the Institute for Systems Biology in Seattle.
“The chance that you’re identifying something [as a mutation] that is actually an error is pretty high,” Galas says. “The major advantage of sequencing in a family is you can reduce the error rate dramatically.”