In the present study, we completed a GWAS of AD criterion count and the related phenotypes of “MAXDRINKS,” or maximum number of alcoholic beverages taken in any 24-hour period over a subject’s lifetime (Saccone et al., 2000), and flushing after drinking alcohol, in a Thai population collected for study of methamphetamine genetics. This was feasible because although the focus in the parent study was on methamphetamine dependence, we used the Semi-Structured Assessment for Drug Dependence and Alcoholism (SSADDA) for assessment. The SSADDA is a comprehensive diagnostic interview designed for genetic studies of substance dependence and related phenotypes (Pierucci-Lagha et al., 2007, Pierucci-Lagha et al., 2005). We previously developed a Thai version of the SSADDA, which was translated and validated in genetic studies of opioid dependence in Northern Thailand, where it was shown to have both high inter-instrument validity and inter-rater reliability for that trait (Malison et al., 2011). There is a high level of comorbidity between methamphetamine dependence and AUDs and a high rate of AUDs in Thailand overall (9.1% in males and 1.0% in females in 2010 (World Health Organization, 2014)), and accordingly the sample is highly informative for study of alcohol-related traits.
