The phenotypic difference discards sib-pair QTL linkage information
- Univ. of California, San Diego, CA (United States)
Kruglyak and Lander provide an important synthesis of methods for (IBD) sib-pair linkage mapping, with an emphasis on the use of complete multipoint inheritance information for each sib pair. These procedures are implemented in the computer program MAPMAKER/SIBS, which performs interval mapping for dichotomous and quantitative traits. The authors present three methods for mapping quantitative trait loci (QTLs): a variant of the commonly used Haseman-Elston regression approach, a maximum-likelihood procedure involving variance components, and a rank-based nonparametric procedure. These approaches and related work use the magnitude of the difference in the sibling phenotype values for each sib pair as the observation for analysis. Linkage is detected if siblings sharing more alleles IBD have similar phenotypes (i.e., a small difference in the phenotype values), while siblings sharing fewer alleles IBD have less similar phenotypes. Such techniques have been used to detect linkage for a number of quantitative traits. However, the exclusive reliance on the phenotypic differences may be due in large part to historical inertia. A likelihood argument is presented here to show that, under certain classical assumptions, the phenotypic differences do not contain the full likelihood information for QTL mapping. Furthermore, considerable gains in power to detect linkage can be achieved with an expanded likelihood model. The development here is related to previous work, which incorporates the full set of phenotypic data using likelihood and robust quasi-likelihood methods. The purpose of this letter is not to endorse a particular approach but to spur research in alternative and perhaps more powerful linkage tests. 17 refs.
- OSTI ID:
- 518563
- Journal Information:
- American Journal of Human Genetics, Vol. 60, Issue 3; Other Information: PBD: Mar 1997
- Country of Publication:
- United States
- Language:
- English
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