OUTLINE: Two important aspects of the methodologies that will be employed for the analysis of SNPs associated with GVHD are throughput efficiency to be able to perform the assays on a reasonable number of samples as well as having the ability to add or remove SNPs to the assay panel. While a genome-wide association study to identify variants associated with GVHD would offer an unbiased approach, our patient cohort size would not allow significant statistical power in the study. Therefore, a more targeted approach using two established technologies is proposed.