Coeliac disease
Currently, in assessing diseases like Coeliac disease a definite diagnosis is often not possible and statistical considerations are relied upon. The knowledge of frequencies in populations, particularly among ancestors of immigrants can aid patient and physician as to the potential risks. An example, one publication states that the western regions of Ireland have the highest coeliac disease rate in the world. Plotting the frequency of DQ2.5 from any part of Western Europe to the Irish one sees the frequency gradient progressing toward the north and west of Ireland; therefore, a high rate of coeliac disease is not unexpected in Western Ireland. People with many common ancestors from Ireland share similar risks of disease.