MODEL-BASED PREDICTION OF DIABETES INCIDENCE IN BB OK RATS

In the BB/OK rat strain, the incidence of diabetes (in the context of animal diabetes defined as the percentage of animals developing diabet es up to the age of 200 days) is related to the sex distribution withi n litters and to the phenotype of the parents. On the basis of these o bservations, an algorithm was developed to predict the incidence of di abetes of an inbred generation as the percentage of diabetic animals o f a given inbred generation. Thus, the incidence of diabetes was analy sed in 25 inbred generations of our BB/OK colony according to sex rati o and the phenotype of parents, which is thought to be an important ge netic factor for diabetes onset in the offspring. On the basis of a si ngle gene model, the Maximum-Likelihood method was used to predict the incidence of diabetes (average and standard deviation). The practicab ility of this approach was checked by a retrospective calculation of M aximum-Likelihood estimates and their comparison with the diabetes inc idence as observed in the individual inbred generation. The average di fference between the estimated and observed values was 5.4 % which sho ws the practicability of the proposed algorithm and confirms the domin ance of genetic factors in the development of diabetes in this BB rat subline.