In conclusion, our results emphasize that genetic variation in 5-HTTLPR is relevant to the development of depressive symptomatology. However its effects are expressed through a multilevel network of interactions among genes, and between genes and the environment. No doubt there are several other important modifying variables still to be discovered [43,44,45]. Our results also indicate how methodological differences between studies may obscure or mask important associations and emphasize the need for further studies applying sophisticated designs and alternative mathematical methods to clarify and deepen our understanding of the role of genetic risk factors for depression and anxiety.
