Studies of patterns of major depression in families suggest that 50 to 70% of the predisposition to major depression is caused by genes. People with recurrent depression and earlier ages of onset have more relatives with depression. There are probably at least several interacting genes, rather than a single gene as in some disorders. The identification of predisposing genes is likely to lead to greater understanding of the brain mechanisms involved in severe depression. This could lead to the discovery of new treatments.

This study will create a DNA collection to permit qualified scientists to search for depression-related genes. More than 750 families with at least two siblings who have experienced major depression are needed for the study.

Participants in this study will be interviewed about psychiatric and family history, and will be asked for a small blood specimen. Interviews can be conducted in person or by telephone. For telephone interviews, blood sample collection will be arranged at a location and time convenient for the participant. Participants will also be asked for help in inviting other family members to participate. No family member will be contacted without the permission and assistance of another participating family member.

Inclusion Criteria:

• Families that have at least TWO ADULT SIBLINGS (brother/brother; sister/sister; brother/sister) who have experienced major depression.
• Depression must be RECURRENT (more than one episode).
• Depression must have started at age 30 or less in one sibling, and at age 40 or less in the other sibling.

Exclusion Criteria:

• Participants cannot have Bipolar I (manic-depressive) disorder or schizophrenia.