Power comparison of various sibship tests of association

There are several tests available for use with family studies to test if there is significant evidence of association with a particular disease gene locus, especially of HLA. We have used large simulations to compare the powers of tests using criteria N, R, T, PR, WP and some new tests involving both affecteds and unaffecteds in a sibship. It was found that tests using both affected and unaffected siblings were often more powerful.