Unbiased discordant sib-pair tests when parental genotypes are missing

Population admixture and stratification are potential sources of confoundin g in a variety of statistical analyses of genetic data, Many approaches to adjusting for such confounding have been developed in the context of associ ation analyses. These approaches may generally be viewed as relying on nonp arametric null hypotheses that specify certain, sometimes incompletely obse rved, conditional distributions; the conditional distributions are used to normalize test statistics to have expectation zero under the null hypothesi s. Here, with a very simple example, it is shown that there is potentially information that is free of confounding, but that is not recovered by such normalized statistics. An approach presented here in the context of the sim ple example might be extended to methods for recovering information in more complex settings. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 105:57-59, 2 001. (C) 2001 Wiley-Liss, Inc.