Markov chain Monte Carlo linkage analysis of a complex qualitative phenotype

We tested a new computer program, LOKI, that implements a reversible jump M arkov chain Monte Carlo (MCMC) technique for segregation and linkage analys is. Our objective was to determine whether this software, designed for use with continuously distributed phenotypes, has any efficacy when applied to the discrete disease states of the simulated data from the Mordor data from GAW Problem 1. Although we were able to identify the genomic location for two of the three quantitative trait loci by repeated application of the sof tware, the MCMC sampler experienced significant mixing problems indicating that the method, as currently formulated in LOKI, was not suitable for the discrete phenotypes in this data set. ((C)) 1999 Wiley-Liss, Inc.