Complex Segregation Analysis on Multi-Modal Distributions

By using sib-pairs and parent-pairs data, Tai and Gross (1988) proposed a method to test the existence of a 2-allele major locus for a quantitative trait. This method is extended to include three alleles at a major locus in this paper. One may perform this extension in a feasible and practical manner. To show the advantage of this extension, a simulated data set of nuclear families from a 3-allele ordered dominant (i.e., A > B, A > W and B > W in our notation) major locus model for a quantitative trait is analyzed by a 2-allele codominant major locus mixed model and a 3-allele ordered dominant major locus mixed model. The result shows that our method can distinguish between ambiguous trimodal distributions.