Figure 1.
Simplified representation of a region in the genome identified in an association study by a tag variant (#3). The black triangle surrounding the red pixels marks a region of linkage disequilibrium, in which there is little genetic recombination and the variants 1-5 tend to travel together. Although #3 is the variant that was associated with disease, further mapping demonstrated that variant #5 had a stronger association with disease and was found in a coding region for gene 2. Therefore, variant 5 is the causal variant in the study. Functional studies can now be performed to determine how variant 5 disrupts gene function and causes disease.