Genetics of Mood Disorders

Mood disorders are common diseases of major public health importance, contributing to 11% of all inabilities worldwide. Genetic factors are known to play an important role in infl uencing susceptibility to Mood disorders: indeed, formal genetic studies suggest that the risk for first-degree relatives of an affected proband is about threefold higher than the overall population for Major depressive disorder and tenfold higher for bipolar disorder. In the last years, molecular genetic studies provided an extremely large number of findings, even if often confl icting and not consistent. After a brief methodological introduction about genetic study designs, the current knowledge derived from research on mood disorders will be reviewed, particularly as regards genomic regions of interest and genes probably involved in such diseases. Indeed, some chromosomal areas have been repeatedly associated to mood disorders, as well as some interesting genes have been tested. Other genes have received promising evidence and further research is thus needed in order to establish their involvement in mood diseases. Finally, a brief discussion will be focused on the utility to employ more complex research designs in order to disentangle confl icting findings. Mood disorders are complex and heterogeneous disorders, thus gene—gene, gene—environment interactions and endo-phenotypes investigations will probably produce more robust findings.