The purpose of this book is to illustrate a new statistical approach to
test allelic association and genotype-specific effects in the genetic
study of diseases. There are some parametric and non-parametric methods
available for this purpose. We deal with population-based association
studies, but comparisons with other methods will also be drawn,
analysing the advantages and disadvantages of each one, particularly
with regard to power properties with small sample sizes. In this
framework we will work out some nonparametric statistical permutation
tests and likelihood-based tests to perform case-control analyses to
study allelic association between marker, disease-gene and environmental
factors. Permutation tests, in particular, will be extended to
multivariate and more complex studies, where we deal with several genes
and several alleles together. Furthermore, we show simulations under
different assumptions on the genetic model and analyse real data sets by
simply studying one locus with the permutation test.