INCORPORATING CROSSOVER INTERFERENCE INTO PEDIGREE ANALYSIS USING THECHI(2) MODEL

Crossover interference is now known to exist in humans but to date has been ignored in routine genetic mapping because of the computational burden involved. In a recent paper by Weeks et al. [Hum Hered 1993;43: 86-97], interference was accounted for by the use of a variety of mult ilocus feasible map functions and a crossover model of Goldgar and Fai n [Am J Hum Genet 1988;43:38-45]. In this paper, we present an alterna tive approach to incorporating crossover interference into multilocus likelihood computation, by modelling the underlying chiasma process di rectly using the chi(2) model, supplemented by an assumption of no chr omatid interference. This procedure was applied to the same CEPH conso rtium chromosome 10 data set that was analyzed by Weeks et al. A fit t o the data was achieved which was significantly better than that offer ed by the no-interference model, and comparable to the best of the alt ernatives considered by Weeks et al, We briefly discuss the relative m erits of the different models for interference.