Melanopsin polymorphisms in seasonal affective disorder /

by Roecklein, Kathryn Ariel

Title of Thesis: Melanopsin Polymorphisms in Seasonal Affective Disorder Kathryn Ariel Roecklein, Master of Science, 2005 Thesis directed by: Kelly J. Rohan, Ph.D. Assistant Professor Department of Medical and Clinical Psychology Seasonal affective disorder (SAD) is characterized by winter depressive episodes and springtime remission. SAD may result from a genetically-mediated abnormal response to low light availability during winter. One candidate gene for SAD is melanopsin, a non-visual, circadian photopigment. The present study determined the frequency of a genetic polymorphism in melanopsin (P10L) in individuals with SAD (n = 36) compared to two groups: gender-matched controls with no history of depression and minimal seasonality (n = 22) and a larger comparison group of samples obtained from NIH that have been delinked from identifying information (n = 84). The proportion of SAD participants with P10L (28%) did not differ significantly from the comparison group (15%) or nondepressed controls (18%). A post-hoc power analysis revealed that a sample of 200 participants would be required in future studies. If a sufficiently sized sample including gender- and ethnicity-matched controls becomes available, then the study should be repeated. iii Seasonal Affective Disorder and Melanopsin