We should also mention that there are different models that can incorporate between-study heterogeneity in the calculations. We used a conservative approach, the DerSimonian and Laird model, that is the most frequently used random effects model in the literature. Other fully Bayesian approaches may also be used [29], including hierarchical Bayesian models. Some of these models may incorporate also other parameters such as minor deviations from Hardy-Weinberg equilibrium in the observed genotyping data [30]. These models usually tend to give even larger uncertainty and they widen the 95% credibility intervals of the estimates [29].
