title: Accommodating population stratification in case-control association analysis: a new test and its application to genome-wide study on rheumatoid arthritis.
abstract: It is well known that conventional association tests can lead to excessive false positives when there is population stratification. We propose a new test for detecting genetic association with a case-control study design. Unlike some other methods for handling population stratification, we treat the cases as a population and the controls as another one even though each of them may be a mixture of several sub-populations. A likelihood-ratio test is used to test whether the allele frequency of a testing single-nucleotide polymorphism in the case population is the same as that in the control population. This new test is applied to the Genetic Analysis Workshop 16 Problem 1 data on rheumatoid arthritis. Compared with the Pearson chi-square genotype test, the association strength of many single-nucleotide polymorphisms is decreased while the signal at the HLA region on 6p21 is maintained.
authors.affiliation: Program of Public Health Genetics, University of Iowa, 200 Hawkins Drive E177 GH, Iowa City, Iowa 52242 USA. yufang-zhang@uiowa.edu.
authors.forename: Yufang
authors.initials: Y
authors.lastname: Zhang
authors.forename: Xiangjun
authors.initials: X
authors.lastname: Xiao
authors.forename: Kai
authors.initials: K
authors.lastname: Wang