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 women, mean age 49.57 ± 11.87, range 22-69). Brains were analyzed for adequate pH (>6.0) and RNA integrity by optical density (RNA ratio; OD ≥ 1.3) and Agilent bioanalyzer analysis (Agilent Technologies, Palo Alto, CA; RIN expert scoring system ≥ 7) as described.20 Gender, age, MDD vs. control status, pH, RNA ratio and post mortem interval were controlled for in all analyses involving this sample. A square root transformation was applied to SLC6A4 mRNA levels to normalize its positively skewed and kurtotic distribution (pre-transformation skewness = 1.92, kurtosis = 6.45, post-transformation skewness = 0.65, kurtosis = 1.43).
