While identical twins are born with the same set of genes, their lifetime experiences (environment) may differ. These environmental differences may cause small changes in how their genes are regulated (turned on or off). Such changes are called epigenetic modifications. One type of epigenetic modification is called DNA methylation.
This study is recruiting identical twin pairs who differ in their mood histories: one twin has had persistent feelings of sadness or emptiness, and/or loss of interest or motivation at any time in their life, while the other twin has no history of these experiences. DNA methylation will be analyzed to see what differences there are between the twins. Some goals of the study are to better understand how gene regulation may affect mood experiences such as sadness or lack or motivation, and to increase knowledge about how your environment may affect your behavior and health.
Each potential study participant will have a phone interview. If both twins are a good fit for the study and choose to participate, they will do study procedures at home and have a one-hour in-person visit to the University of Washington Medical Center in Seattle. The at-home procedures are completing questionnaires and collecting samples of saliva, stool and toenail clippings. The in-person visit includes a blood draw, urine sample collection, physical measurements, and completing questionnaires.