The demographic and clinical parameters of the cohort and technical parameters of the samples have been described in detail previously20. All procedures involving this cohort were approved by the University of Pittsburgh’s Committee for the Oversight of Research Involving the Dead and Institutional Review Board for Biomedical Research. Consent was obtained from each subject’s next of kin. For all subjects, consensus DSM-IV diagnoses of MDD were made by an independent committee of experienced clinical research scientists at a case conference utilizing information obtained from clinical records, toxicology exam and a standardized psychological autopsy21. The latter incorporates a structured interview, conducted by a licensed clinical psychologist with family members of the index subject, to assess diagnosis, psychopathology, medical, social and family histories, as well as history of substance abuse. All subjects died suddenly without prolonged agonal periods. For consistency across samples and to minimize population stratification and pharmacologic confounds, we focused our analysis on Caucasian individuals and excluded those with ascertained medication use at time of death (ascertained by toxicology screen on peripheral tissue), leaving a final sample of 35 (10
