A weighted test using both extreme discordant and concordant sib pairs for detecting linkage

Statistical procedures using extremely discordant and concordant sib-pairs have been developed for mapping quantitative trait loci in humans. To improve the power of the existing methods, test statistics placing greater weight on the more discordant or more concordant pairs are proposed. Because the optimum choice of weights would depend on the underlying genetic model, which is not usually known, a test with simple weights is suggested. This test is shown to have greater power than the currently available ones for a variety of genetic models.