These findings are limited to the Finnish population-based cohorts, and therefore replications in other samples of other populations should be pursued. With altogether 543 cases and 9616 controls, our study remains very much underpowered, as indicated in the power calculations. Bigger sample sizes are needed, although collection of large samples is rather demanding, and especially for behavioral phenotypes of a relatively special nature, such as ASPD, large samples may materialize at the expense of phenotype homogeneity. The large GWAS's have proven the method a useful tool for identifying genetic loci in complex disease of small individual factor effect sizes, such as in schizophrenia.34 However, GWAS in smaller samples may also reveal important associations, particularly, when the phenotype is accurate, and the suggestive findings may be of value for future studies with larger sample sizes.
