Genetic studies are on to find out exactly which gene causes the problem. But a single one has not been identified. The problem is compounded by the fact that Bipolar Affective Disorder has several clinical presentations that range from Bipolar Affective Disorder I to Bipolar Affective Disorder III. A few researcher suggest that problems with the 8q21 gene could be the major controlling factor for the disease. But different genes can cause the problem in different patients and this is further delaying the research done by doctors.