Recently, a new model has been proposed called the generalized Wright's model (GWM). The GWM involves (k-1)(k+2)/2 number of independent parameters for any k allelic system; out of these, k-1 are gene frequencies and k(k-1)/2 are partial fixation indices, also called partial inbreeding coefficients. All these parameters cannot be estimated from population data on dominant systems such as the ABO system. However, all the parameters are estimable from data on mating type frequencies, for which the mating type probabilities for ABO system are reported in this paper. Seven bodies of data on ABO types are analysed using this method, and inference from such analysis is briefly discussed.