wtest: an R Package for Testing Main and Interaction Effect in Genotype   Data with Binary Traits
  This R package evaluates main and pair-wise interaction effect of single nucleotide polymorphisms (SNPs) via the W-test, scalable to whole genome-wide data sets. The package provides fast and accurate p-value estimation of genetic markers, as well as diagnostic checking on the probability distributions. It allows flexible stage-wise or exhaustive association testing in a user-friendly interface. Availability: The package is available in CRAN, or from website: http://www2.ccrb.cuhk.edu.hk/wtest 
Rui Sun, Billy Chang, Benny Chung-Ying Zee and Maggie Haitian Wang
stat.CO q-bio.QM