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Biostatistics. 2008 Oct;9(4):593-600. doi: 10.1093/biostatistics/kxn007. Epub 2008 Apr 25.

Testing for association on the X chromosome.

Author information

1
Cambridge Institute for Medical Research, University of Cambridge, Wellcome Trust/MRC Building, Addenbrookes's Hospital, Cambridge, UK. david.clayton@cimr.cam.ac.uk

Abstract

The problem of testing for genotype-phenotype association with loci on the X chromosome in mixed-sex samples has received surprisingly little attention. A simple test can be constructed by counting alleles, with males contributing a single allele and females 2. This approach does assume not only Hardy-Weinberg equilibrium in the population from which the study subjects are sampled but also, perhaps, an unrealistic alternative hypothesis. This paper proposes 1 and 2 degree-of-freedom tests for association which do not assume Hardy-Weinberg equilibrium and which treat males as homozygous females. The proposed method remains valid when phenotype varies between sexes, provided the allele frequency does not, and avoids the loss of power resulting from stratification by sex in such circumstances.

KEYWORDS:

Genetic association studies

PMID:
18441336
PMCID:
PMC2536723
DOI:
10.1093/biostatistics/kxn007
[Indexed for MEDLINE]
Free PMC Article

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