The authors wish to retract the 10 November 2011 article cited above, prepublished on 14 September 2011, because they miscalculated some of the HLA allele frequencies because of missing information on split alleles (mainly in controls). Individuals with missing split allele information were erroneously left out of the analyses, which caused some (3/11) of the reported significant associations to be incorrect. The authors noticed the errors themselves and directly contacted the editors of Blood. It was an honest mistake, not fraud or scientific misconduct. The authors sincerely apologize to the readers, reviewers, and editors of Blood for making this unfortunate mistake. This retraction was prepublished online on 20 January 2012.