[Use of case-parents trio for epidemiological studies of association between genetic polymorphisms and complex diseases].

In case-control studies, spurious associations between allelic variants in candidate genes and disease may arise as a result of population stratification by ethnicity. In epidemiological terms, the ethnic group would act as a confounding factor if both the genotype frequency and the incidence/prevalence of a given chronic disease vary across ethnic groups. Population stratification is a key element in the study of population dynamics and the knowledge of the disparity in health-related conditions among strata has important social and public health implications. However, it would not be scientifically correct to conclude a causal gene-disease association in situations in which the association arises as a consequence of a particular population structure. Although the relevance and magnitude of the bias derived from this confounding, effect would be different depending on the population considered, there has been an increased use of study designs such as the case-parent study, that avoids the effect of population stratification by ethnicity. In this article, we review the analysis of case-parent trios using unrelated affected cases as an epidemiological study design for testing association between genetic polymorphisms and disease.