causality, complex genetic disease

"Are we there yet?": Deciding when one has demonstrated specific genetic causation in complex diseases and quantitative traits. by Page GP et al, Am J Hum Gen 2003
back in 2003 was published nice overview of the causality concept of complex multifactorial polygenic diseases. author mentions Hill´s criteria for causality in epidemiological research, as well as those of Koch´s postulates, along with the review of causality concepts from the scientific to philosophical standpoint. Page discusses the common problem of causality vs association, and gives a step-by-step detailed treatise of what can be cause of a positive genetic association.

here you can read article in AJHG 2003

sample size, general, genetic association, SW

discussion of/ and practical guide on sample size determination - in general
by Lenth, Effective sample size determination
Lenth is author of Java based software for sample size/ power estimation. it is very intuitive
classical web-based calculators of power and sample size for GENETIC ASSOCIATION studies are:
Purcell´s site:
Genetic power calculator

and Derek Gordon´s calculator, allowing researchers to take into account possible genotypic error and/or misclassification errror:

PAWE - Power for Association With Errors

also see Gordon´s article on factors affecting statistical power in the detection of genetic association which was published as part of the JCI review series on genetics of complex diseases.