Mapping quantitative trait loci using both extremely discordant and concordant sib pairs: a unified approach for meta-analysis

Extremely discordant (ED) and concordant (EC) sib pairs are recommended by Risch and Zhang ( 1995, 1996 ) and Zhang and Risch ( 1996 ) for the detection of linkage on the basis of power analysis. They did not, however, include both discordant and concordant sib pairs simultaneously in the test statistic. We construct a new test statistic including both types of sib pairs. The size of the sample needed to identify the sib pairs and parents, who will be genotyped, is reduced substantially by including a hybrid of discordant and concordant sib pairs in the analysis. This mixed design also provides a common parameter that simplifies meta-analysis of sib pair linkage studies.