The latest disease to be put under the scrutiny of a large genome-wide association study is psoriasis--see articles here, here, and here. These are mostly standard studies, but once again I'm struck by the effect of the MHC (HLA) region (see the figure). It was well-known, of course, that variation in HLA affects all manner of immunity-related phenotypes, but what's becoming clear is that this variation has much larger effects than other loci in the genome. I find this somewhat surprising--associations with MHC variability were identified because typing HLA was feasible many years ago; well before genome-wide association mapping with SNPs was even considered. This could be a case where, in the analogy to the man searching for the lost keys in the dark, looking under the lamppost was actually the best bet.

Labels: Genetics