INTERVAL MAPPING OF QUANTITATIVE TRAIT LOCI THROUGH ORDER-RESTRICTED INFERENCE

An order-restricted version of the standard interval mapping procedure is introduced. The usual LOD scores (base 10 logs of likelihood ratio s) used in interval mapping are replaced with LOD scores based on rest ricted likelihood ratio test statistics, which make use of known order ings in the genotype effects at the putative quantitative trait loci ( QTL). Simulations demonstrate that individual tests based on the restr icted LOD scores can be more powerful than tests based on the standard LOD scores. The new procedure appears to improve QTL detection capabi lity and estimates of both position and genotype effects in certain ci rcumstances, Techniques from order-restricted inference are combined w ith the EM algorithm to estimate genotype effects and compute the rest ricted LOD scores.