Power of affected sibling method tests for linkage

When the mode of inheritance of a disease susceptibility (DS) gene is unknown, the affected sibling method can be applied to study whether a DS gene and a marker gene are linked. This method considers how k affected siblings (k > or = 2) share marker alleles identically by descent from their parents. Several nonparametric and likelihood ratio test statistics have been proposed for the use with affected sibling marker gene data. We compare the power of these proposed tests for linkage under different genetic models via simulation. We find that, in general, the likelihood ratio tests are slightly more powerful, but the gain in power may not warrant the additional computation burden imposed.