The main novel finding from our study is the association between the A allele of rs6943555 in the AUTS2 gene and completed suicide. We observed overrepresentation of the A alleles, AA and AT genotypes in the suicide group compared to controls. After dividing cases into those who committed suicide under influence of alcohol and those without such influence, the association was observed only among cases with blood ethanol concentration over 20 mg/dl. The association between the A allele of rs6943555 and suicide under influence of alcohol was subsequently replicated in a second cohort of cases.
The direction of the observed association of the rs6943555 A allele with suicide is opposite to the association with alcohol consumption reported previously 
. We hypothesize that rs6943555 A allele may be linked to an adverse reaction to ethanol which would explain its association with lower alcohol consumption in general population (ref. 
and the trend observed by us among the WOBASZ subjects) as well as the predisposition to suicide under influence of ethanol observed by us. Schumann et al.
found increased expression of AUTS2
in human prefrontal cortex among the A vs. T allele carriers indicating that the excessive activity of the AUTS2 protein may be responsible for these effects 
. Furthermore, inactivation or down-regulation of the AUTS2
gene in Drosophila melanogaster
caused reduced sensitivity to ethanol despite similar internal ethanol concentrations after ethanol exposure in mutant and wild type flies 
. In the context of our observations this suggests a scenario where the carriers of the A allele have higher expression of AUTS2
and are more sensitive to ethanol induced negative emotions leading to suicide. Such processes could involve impulsivity, impaired decision making and emotion dysregulation after consumption 
Although we show that rs6943555 is associated with suicide it is not clear whether this is a primary association or an effect of marker(s) in linkage disequilibrium. It is also possible that multiple variants in AUTS2
have independent effects of suicide risk. Since we tested a single marker our data cannot answer this question. However, it should be emphasized that the association between rs6943555 and alcohol consumption which prompted our work emerged from an extensive genome-wide study in which ~2,5 mln. SNPs were analyzed either directly or by imputation 
. In particular Affymetrix 500 K which was the most frequently used chip among studies selected for meta-analysis by Schumann et al. allows to type 184 SNPs within AUTS2
and this number is further increased by imputation procedures used 
. Whereas the Schumann et al. do not provide a detailed list of SNPs within AUTS2
which were analyzed Fig. S3A from the article 
indicate that in addition to rs6943555 a substantial number of other SNPS in AUTS2
was covered. Furthermore, in addition to mapping the primary association via known SNPs Schuman et al. also performed a screen for nonsynonymous genetic variants in the exons most proximal to rs6943555 in 200 individuals 
. Thus, although there is clearly a need for comprehensive evaluation of all AUTS2
variants vs. suicide risk it is possible that rs6943555 or a very closely linked SNP will remain the primary candidate.
It is increasingly recognized that pathophysiology of mental disorders is heterogenic and multifactorial 
. Shared behavioral characteristics of many of them may be associated with shared underlying molecular mechanisms. Provided they are replicated in other populations our results should lead to a better understanding of the genetic risk factors, which play a role in the pathogenesis such psychiatric phenotypes as suicide, alcohol sensitivity and autism.