title: Density-based clustering in haplotype analysis for association mapping.
abstract: Clustering of related haplotypes in haplotype-based association mapping has the potential to improve power by reducing the degrees of freedom without sacrificing important information about the underlying genetic structure. We have modified a generalized linear model approach for association analysis by incorporating a density-based clustering algorithm to reduce the number of coefficients in the model. Using the GAW 15 Problem 3 simulated data, we show that our novel method can substantially enhance power to detect association with the binary rheumatoid arthritis (RA) phenotype at the HLA-DRB1 locus on chromosome 6. In contrast, clustering did not appreciably improve performance at locus D, perhaps a consequence of a rare susceptibility allele and of the overwhelming effect of HLA-DRB1/locus C, 5 cM distal. Optimization of parameters governing the clustering algorithm identified a set of parameters that delivered nearly ideal performance in a variety of situations. The cluster-based score test was valid over a wide range of haplotype diversity, and was robust to severe departures from Hardy-Weinberg equilibrium encountered near HLA-DRB1 in RA case-control samples.
authors.affiliation: Department of Epidemiology and Biostatistics, Case Western Reserve University, Wolstein Research Building, 2103 Cornell Road, Room 1300-C, Cleveland, Ohio 44106, USA. rigo@darwin.case.edu
authors.forename: Robert P
authors.initials: RP
authors.lastname: Igo
authors.forename: Douglas
authors.initials: D
authors.lastname: Londono
authors.forename: Katherine
authors.initials: K
authors.lastname: Miller
authors.forename: Antonio R
authors.initials: AR
authors.lastname: Parrado
authors.forename: Shannon R E
authors.initials: SR
authors.lastname: Quade
authors.forename: Moumita
authors.initials: M
authors.lastname: Sinha
authors.forename: Sulgi
authors.initials: S
authors.lastname: Kim
authors.forename: Sungho
authors.initials: S
authors.lastname: Won
authors.forename: Jing
authors.initials: J
authors.lastname: Li
authors.forename: Katrina A B
authors.initials: KA
authors.lastname: Goddard