'Rare Diseases Matter'

At Genetic Future, Daniel MacArthur says there are thousands of genetic diseases, like Huntington's, that, while individually rare, collectively add up to "a tremendous burden of suffering." But finding disease-causing mutations has so far been a long and arduous process based on linkage analysis — and for some diseases that are found only in small families or are caused by spontaneous genetic changes rather than inherited ones, linkage analysis is "impossible," he adds. Over the past few years, however, advances in sequencing technologies have provided researchers an alternative to linkage analysis. "Rather than first looking for the regions of the genome that are linked to the disease, cheap sequencing offers a simple, brute force solution: look at all of the genes in a patient's genome, see which ones contain a likely damaging mutation, and then investigate those genes to see which is most likely to cause the patient's disease," MacArthur says. And the popularization of exome sequencing has made the hunt for disease genes even simpler. In fact, exome sequencing may even prove to be a long-awaited answer to the problem of understanding gene function, he adds, saying, "Never before has a single technique promised to reveal so much about genetic disease in such a short space of time. For geneticists, and for rare disease patients, these are exciting times indeed."