Background A robust body of evidence from family, twin and adoption studies
demonstrates the importance of genes in the pathogenesis of bipolar disord
er. Recent advances in molecular genetics have made it possible to identify
these susceptibility genes.
Aims To present an overview for clinical psychiatrists.
Method Review of current molecular genetics approaches and emerging finding
s.
Results Occasional families may exist in which a single gene plays a major
role in determining susceptibility. but the majority of bipolar disorder in
volves more complex genetic mechanisms such as the interaction of multiple
genes and environmental factors. Molecular genetic positional and candidate
gene approaches are being used for the genetic dissection of bipolar disor
der. No gene has yet been identified but promising findings are emerging. R
egions of interest include chromosomes 4p16, 12q23-q24, 16p13, 21q22, and X
q24-q26. Candidate gene association studies are in progress but no robust p
ositive findings have yet emerged.
Conclusion It is almost certain that over the next few years the identifica
tion of bipolar susceptiblity genes will have a major impact on our underst
anding of disease pathophysiology, This is likely to lead to major improvem
ents and treatment in patient care. but will also raise important ethical i
ssues.