A COMPREHENSIVE ANALYSIS OF COMPLEX TRAITS IN PROBLEM 2A

We used descriptive analysis to investigate the relationship between a ffection status and five quantitative traits (Q1-Q5) in Problem 2A and results suggested the five quantitative traits fall into two groups. The first group comprised three strongly correlated traits, Q1-Q3, whi ch underlie affection status, and the second group comprised Q4 and Q5 , which are not directly related to affection status. Segregation and linkage analyses of traits Q1-Q3 and affection status from the first r eplicate detected one of the major loci for Q1 (MG1) linked to marker 14 on chromosome 5 (D5G14). Because our segregation analysis failed to show evidence of a major locus effect on Q2, and we overlooked the in teraction between MG3 and sex, we did not detect either MG2 or MG3. Us ing Haseman-Elston sib-pair analysis [Haseman and Elston, 1972], we al so examined the statistical power of Q1 and type I error rate (using t he environmental factor as an index), for the remaining 199 replicates in the context of a genome screen. (C) 1997 Wiley-Liss, Inc.