Since bipolar patients display significant clinical variability, which may reflect underlying genetic heterogeneity, the use of the DSM-IV diagnosis of BD as a phenotype may not have the best power to detect causal genes. We have explored the use of temperament to define subtypes of BD and create more homogenous groups of patients with more similar clinical courses. These subgroups of patients may also show less genetic heterogeneity, which may facilitate the detection of the underlying genetic variants.
