Comparison of 'model-free' and 'model-based' linkage statistics in the presence of locus heterogeneity: Single data set and multiple data set applications
J. Huang et Vj. Vieland, Comparison of 'model-free' and 'model-based' linkage statistics in the presence of locus heterogeneity: Single data set and multiple data set applications, HUMAN HERED, 51(4), 2001, pp. 217-225
Earlier work [Knapp et al.: Hum Hered 1994;44:44-51] focusing on affected s
ib pair (ASP) data established the equivalence between the mean test and a
test based on a simple recessive lod score, as well as equivalences between
certain forms of the maximum likelihood score (MLS) statistic [Risch: Am J
Hum Genet 1990;46:242-253] and particular forms of the lod score. Here we
extend the results of Knapp et al, [1994] by reconsidering these equivalenc
es for ASP data, but in the presence of locus heterogeneity. We show that R
isch's MLS statistic under the possible triangle constraints [Holmans: Am J
Hum Genet 1993;52:362-374] is locally equivalent to the ordinary heterogen
eity rod score assuming a simple recessive model (HLOD/R); while the one-pa
rameter MLS assuming no dominance variance is locally equivalent to the (ho
mogeneity) recessive led. The companion paper (this issue, pp 199-208) show
ed that when considering multiple data sets in the presence of locus hetero
geneity, the HLOD can suffer appreciable losses in power. We show here that
in ASP data, these equivalences ensure that this same loss in power is inc
urred by both forms of the MLS statistic as well, The companion paper also
introduced an adaptation of the led, the compound lod score (HLOD/C). We co
nfirm that the HLOD/C maintains higher power than these 'model-free' method
s when applied to multiple heterogeneous data sets, even when it is calcula
ted assuming the wrong genetic model. Copyright (C) 2001 S. Karger AG, Base
l.