Restrictions on Components of Variance for Epistatic Models
Tiwari HK, Elston RC
Department of Epidemiology and Biostatistics, Rammelkamp Center for Education and
Research, Case Western Reserve University, Cleveland, Ohio.
Theoretical Population Biology, 54(2):161-174 (1998).
Abstract
If a disease is caused by several loci, then the additive variance at each locus may
represent only small portions of the total genetic variance, while epistatic variance
components may explain a significant amount of the total genetic variance. In this paper
we first give simple general formulations to derive all the components of total genetic
variance in a random sample for any multilocus model. We then derive these
components for a series of fifteen models that have been proposed as being the
two-allele two-locus models most likely for disease. We discuss the restrictions and
limitations on the penetrance and the gene frequencies, implied by the disease
prevalence, for each model. We investigate the relative magnitudes of the components
of variance for the various models and show that in six of the models one or other of the
epistatic variance components can be larger than each of the other components. It is
suggested that investigations be undertaken to develop appropriate sampling and
analytical techniques to detect these variance components by linkage analysis.
Variance component linkage analysis