passing bipolar down

Hello, I come from a family of 6 children, one, a brother has bipolar.   I do not have bipolar, but suffer with depression, and have most of my life and take meds for.  I have 3 children, my youngest daughter has bipolar.  My sons are both married and have 2 children each.  One son has a son and a daughter, and his wifes mother has bipolar.

My question is:    what are the odds that one of my sons children will develop bipolar?  also is there a prenatal test that could tell this information?

[Lisa Kessler, MS, CGC]

I hope that the following background information is helpful.  Both bipolar disorder and major depressive disorder are complex conditions caused by a combination of genetic and environmental factors.  There is currently no clinical genetic testing available for bipolar disorder which can be used as prenatal testing.  Research testing for bipolar disorder is available at University of Pittsburgh Medical Center at [phone], and this lab accepts contact from patients/families.
It may help to meet with a genetic counselor who can thoroughly review the family history and provide you with a personalized risk estimate for your son.  Some general information for families is available in the literature.  People with a first degree relative (parent, child or sibling) with major depressive disorder are 2-3 times more likely to get a major depressive disorder compared to someone without a family history.  Family members of people with bipolar disorder are at increased risk for both bipolar and unipolar disorders, but the reverse has not been found.  The chance that someone will develop bipolar disorder in the general population is 1-5%.  The chance that someone with a first degree relative with bipolar disorder will develop the condition is 4%-18%.   You can find a genetic counselor through the website of the National Society of Genetic Counselors.  Best wishes to you and your family.