Moreover, a polymorphism does not necessarily regulate the nearest gene. For instance, a systematic study of complex phenotypes and associations in the GWAS Catalog found evidence that affected genes are often up to 2 MB from the associated SNP.118 To address this issue, a number of techniques have been developed, usually variations on the chromosome capture technique,119 which allows the isolation and identification of chromosome sequences that interact with one another. While the data are dependent on the tissue in which the experiment was performed, the state of the art is quite advanced now, and a browser has been constructed to allow visualization of this interacting regions information (http://promoter.bx.psu.edu/hi-c/).120
