Correlation between quantitative traits and correlation between corresponding LOD scores: detection of pleiotropic effects

BACKGROUND: We address the question of whether statistical correlations among quantitative traits lead to correlation of linkage results of these traits. Five measured quantitative traits (total cholesterol, fasting glucose, HDL cholesterol, blood pressure, and triglycerides), and one derived quantitative trait (total cholesterol divided by the HDL cholesterol) are used for phenotype correlation studies. Four of them are used for linkage analysis. RESULTS: We show that although correlation among phenotypes partially reflects the correlation among linkage analysis results, the LOD-score correlations are on average low. The most significant peaks found by using different traits do not often overlap. CONCLUSION: Studying covariances at specific locations in LOD scores may provide clues for further bivariate linkage analyses.