Symptoms of schizophrenia develop in more than 1:200 people, in all cultures, while 2- 4% of the population may experience major depression at some time in their life. Mild and moderate depression are, of course, much more common. Sometimes illnesses run in families and show higher concordance among identical compared to non-identical twins suggesting an important genetic contribution to risk. Molecular genetics now gives us the tools to analyse genetic risk using DNA samples donated by people with schizophrenia, bipolar disorder, depression, autism, attention deficit, obsessive-compulsive disorder, anxiety, anorexia, substance use and post-traumatic stress. These disorders are the focus of ongoing international collaborations performing genome -wide association studies. Results to date are remarkable. Genes have been found that contribute to these illnesses and it is hoped this new knowledge could lead to novel drug targets and new preventative interventions. The use of advanced techniques such as gene editing and improved possibilities for accurate prenatal testing are raising important ethical questions that require informed public discussion and debate.
Prof. Douglas Blackwood is Professor of Psychiatric Genetics at the University of Edinburgh