Thursday, July 19, 2007

The continuing success of genome-wide association studies   posted by p-ter @ 7/19/2007 08:05:00 PM

The first wave of genome-wide association studies has largely been confined to "big-name" diseases-- things like diabetes, heart disease, breast cancer, etc. There's a financial reason behind this, of course-- funding agencies like the NIH are most interested in diseases of major public health import, as are companies like DeCode. But in the next few years, there's no doubt it will become clear that any phenotype is amenable to this sort of genetic dissection. Genome-wide association studies are an important new tool in the biologist's toolkit, and it's worth noting that genetic data is (or will be) much richer in humans than in any other organism.

A couple new papers add towards what could eventually be a detailed understanding of the genetics of human phenotypic variation: first, a genome-wide association study of "restless leg syndrome", an ill-defined, heterogeneous disorder. The authors describe it thusly:
Nightwalkers, as individuals with RLS call themselves, are forced to move their legs during periods of rest especially in the evening and night to relieve uncomfortable or painful sensations in the deep calf. This diurnal variation leads to impaired sleep onset, and the periodic leg movements during sleep in the majority of patients contribute to sleep disruption and a reduced quality of life as a major consequence
The association study identified three risk factors near genes about which, as tends to be the case in these studies, very little is known. However, these are leads that will be immediately followed up, and likely with great impact.

Second, see this GWA study of "gallstone disease". Like restless leg syndrome (which has a prevalence of around 2-3%), this is hardly a rare phenotype-- the authors give the prevalence as between 10 and 20% of the population in industrialized nations. Though characterized as "diseases", both of these phenotypes lie within the range of normal human variation.

As prices on this sort of technology drops, the most interesting results will not necessarily come from the big genome centers, but rather from the people that choose to study interesting phenotypes. There's plenty of low-hanging fruit to be picked...

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