EMPIRICAL AFFECTED-SIB-PAIR STATISTICS - 2 SIMULATION STRATEGIES

We compare two simulation procedures used to determine empirical distr ibutions of three affected sib-pair test-statistics in family samples with missing parental marker information. P1 and P2 procedures differ according to whether affected sibs' genotypes are ignored (P1) or acco unted for (P2) to generate the unknown parental genotypes. Overall, ou r results show that P2 procedure performs better than P1, particularly when marker heterozygosity is high (H = 75%) or when marker data from unaffected siblings are available with low marker heterozygosity (H = 50%). These results are similar for all affected sib-pair tests. (C) 1997 Wiley-Liss, Inc.