LRASSOC 1.1 – Analysis of Case-control Data for Diseases with Two Susceptiblity Loci



LRASSOC suite deals with the situation where we have a case-control sample of affected and unaffected individuals with their marker genotypes for 2 biallelic marker loci. These 2 marker loci may be in linkage disequilibrium with 1 or 2 biallelic disease susceptibility loci and therefore affect disease risk through association or may themselves be disease susceptibility loci. We are interested in modelling the effects of the genotype on the probability of disease risk in order to draw conclusions regarding the nature of the joint effect of the loci. Among the issues we may wish to investigate are whether either of the 2 loci actually has an effect on disease risk, the strength and statistical significance of any effect, the nature of such an effect e.g is the effect additive on some scale or do the alleles at the same loci interact in a dominance effect. We also want to compare single and joint locus models to investigate how the strength and significance of the effect of each locus is affected by the presence or absence of the other in a model and, a related point, whether the additive and dominance effects of two loci are independent or whether they interact (often called epistasis in this context).



Bernard North


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North B.V., Sham P.C. and Curtis D.
Application of logistic regression to case-control association studies involving two causative loci“,
Human Heredity (2005) 59: 79-87.

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