Power of variance component linkage analysis to detect quantitative trait loci

Jeff T. Williams, J. Blangero

    Research output: Contribution to journalArticlepeer-review

    111 Scopus citations


    Expressions are derived for the sample size required to achieve a given power in variance component linkage analysis of a quantitative trait in unascertained samples. For simplicity as additive model, comprising effects due to a single QTL, residual additive genetic factors, and individual-specific random environmental variation, is considered. Equations are given relating sample size to trait heritability for sibpairs, sib trios, nuclear families having two and three sibs, and arbitrary relative pairs. The effects of nonzero residual additive genetic variance and parental information are discussed, and a scale relationship for sample sizes with sibships and nuclear families is derived. For larger sampling structures such as extended pedigrees the inheritance space is randomly sampled and the relevant equations are solved numerically. Comparitive power curves are presented for sibships of size 2-4 and for extended pedigree of 48 individuals. Simulation results for sibpairs confirm the validity of the theoretical results.

    Original languageEnglish (US)
    Pages (from-to)545-563
    Number of pages19
    JournalAnnals of Human Genetics
    Issue number6
    StatePublished - Nov 1999

    ASJC Scopus subject areas

    • Genetics
    • Genetics(clinical)


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