Modern molecular genetic approaches to psychiatric disease.

Major advances in molecular genetics over the last 15 years have made it possible to identify the genes responsible for human diseases using purely genetic approaches that do not require knowledge about disease pathophysiology. Many successes have been achieved for single gene disorders and methods are being adapted and refined for complex diseases. The main strategies include linkage and association studies to map the position of disease genes followed by investigation of potential candidate genes within these genomic regions. Successes have already been achieved in complex disorders such as diabetes and Alzheimer's disease, and it is almost certain that genes predisposing to the major psychiatric disorders will be identified over the next few years. This will lead to major advances in treatment, prevention and classification of mental illness and is likely to have a dramatic impact on clinical practice.