To do this, you need to know the overall incidence of the disease in the general population. Because of the DiaMond project and the development of standardized incidence registries in each of the countries, T1D incidence data was readily available. For other disorders, I would refer you to epidemiologic literature regarding population incidence rates.

As we saw on slide 11, the overall incidence rate in a population is a weighted average of the rates specific to the subgroups of that population that have and do not have the risk factor of interest. In this situation, we have 3 subgroups – those with 2S, 1S and 0S haplotypes. The overall T1D incidence rate in a population depends on the individual incidence rates for the 3 genotype groups and the proportion of the population that the 3 genotype groups represent.