We report the results of our analyses of the GAW11 Problem 2 data set, using information from three different populations. In the first part of the paper, we used classical population genetic tests to compare affected individuals from the different populations, stratifying on the environmental factors. Thanks to existing linkage disequilibrium in one population, we found one of the disease susceptibility loci. In the second part of the paper, we used the marker association segregation chi 2 method to model the role of this disease susceptibility locus in the different populations and draw some inferences regarding the model used at that locus to generate the data.