Quality control ethnic groups

Polysubstance abusers and controls are collected from research volunteers of each population recruited from the same area. This reduces the risk of stratification problems in each group of subjects. Postmortem brain subjects are obtained from Brain Bank for RNA/cDNA analysis, with careful evaluation for their quality that depend on postmortem interval (PMl), pH and 28S/18S, as well as their age, sex, ethnicity, cause of death, etc. 

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