This is the pre-print (i.e. not peer reviewed) of the article published as Nature Genetics, 2011, 43, pp. 503-504. The definitive published version is available on the publisher's webiste at: http://www.nature.com/ng/index.html ; DOI: 10.1038/ng.83
To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request.