genetic aetiology
Last reviewed 01/2018
There is evidence for the importance of genetics in the aeitology of severe unipolar depression:
- the risk of severe depression in the first degree relatives of a severely depressed patient is 10-15% (compared to 1-2% in the general population)
The evidence for a genetic aetiology of bipolar disorder is stronger:
- the concordance in twin studies is:
- 70% for monozygotic twins reared together
- 70% for monozygotic twins reared apart
- 23% for dizygotic twins
- in adoption studies, risk for bipolar affective disorder stems more from the genetic rather than the adoptive parent
The inheritance is probably non-Mendelian.