Philadelphia, PA, 23 February 2011 – Understanding the genetics of bipolar disorder could lead to new treatments, but identifying specific genetic variations associated with this disorder has been challenging.
A new study in Biological Psychiatry implicates a brain protein called Piccolo in the risk for inheriting bipolar disorder. In the orchestra of neuronal proteins, Piccolo is a member of a protein family that includes another protein called Bassoon. Piccolo is located at the endings of nerve cells, where it contributes to the ability of nerve cells to release their chemical messengers.
http://www.eurekalert.org/pub_releases/2011-02/e-anc022311.php
Manic Muses 
I have read that the disorder often skips a generation or two but no one in my family history has been bipolar. Interesting info I have never seen. Thank you for posting this.