Background: Genetic factors are known to contribute to the etiology of bipolar illness, but the actual genetic mechanisms remain to be clarified.
Methods: This paper reviews the research undertaken to establish the genetic basis of bipolar illness and to elucidate the nature of its genetic predisposition.
Results: The presented findings suggest that bipolar affective disorder is a heterogeneous condition characterized by a complex relationship between the genetic susceptibility and the clinical presentation. Linkage studies have generated promising and replicated findings on chromosomes 18 and 21.
Conclusion: In spite of the methodological difficulties inherent in the genetic study of psychiatric disorders recent investigations have made important advances and promise to identify specific susceptibility genes.