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Friday, August 16, 2013

A Genome-Wide Association Study of Behavioral Disinhibition

We report results from a genome wide association study (GWAS) of five quantitative indicators of behavioral disinhibition: nicotine, alcohol consumption, alcohol dependence, illicit drugs, and non-substance related behavioral disinhibition.

The sample, consisting of 7,188 Caucasian individuals clustered in 2,300 nuclear families, was genotyped on over 520,000 SNP markers from Illumina’s Human 660W-Quad Array.

Analysis of individual SNP associations revealed only one marker-component phenotype association, between rs1868152 and illicit drugs, with a p value below the standard genome-wide threshold of 5 × 10−8. Because we had analyzed five separate phenotypes, we do not consider this single association to be significant.

However, we report 13 SNPs that were associated at p < 10−5 for one phenotype and p < 10−3 for at least two other phenotypes, which are potential candidates for future investigations of variants associated with general behavioral disinhibition.
Biometric analysis of the twin and family data yielded estimates of additive heritability for the component phenotypes ranging from 49 to 70 %, GCTA estimates of heritability for the same phenotypes ranged from 8 to 37 %.

Consequently, even though the common variants genotyped on the GWAS array appear in aggregate to account for a sizable proportion of heritable effects in multiple indicators of behavioral disinhibition, our data suggest that most of the additive heritability remains “missing”.

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