Accuracy of detection of major genes segregating in outbred population by Gibbs sampling using phenotypic values of quantitative traits

Based on the segregation analysis with Gibbs sampling the accuracy to detec t a major gene segregating in outbred populations was investigated by using only phenotypic values and pedigree information. The analyses were carried out with 50 simulated populations (replicates). When a major gene effect w as large enough to make the phenotypic distribution deviate from normal, th e additive allele effect and total major gene variance were correctly estim ated. In populations with a low or moderate effect of the major gene, the a dditive allele effect was systematically underestimated. When no major gene was present, the additive allele effect had a tendency to be overestimated hut the major gene variances turned out to be very close to zero as expect ed. Our results suggest that the major gene variances can be used to detect major genes segregating in a population.