Sonuga-Barke, E. J. S., Oades, R. D., Psychogiou, L., Chen, W., Franke, B., Buitelaar, J. K., Banaschewski, T., Ebstein, R. P., Gill, M., Anney, R. J. L., Miranda, A., Roeyers, H., Rothenberger, A., Sergeant, J. A., Steinhausen, H-C., Thompson, M., Asherson, P., & Faraone, S. V.

Dopamine and serotonin transporter genotypes moderate sensitivity to maternal expressed emotion: The case of conduct and emotional problems in Attention Deficit/Hyperactivity Disorder.
Journal of Child Psychology and Psychiatry, 50, 1052-1063 DOI: 10.1111/j.1469-7610.2009.02095.x.
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Introduction: Mothers’ positive emotions expressed about their children with ADHD are associated with a reduced likelihood of comorbid conduct problems (CP). We examined whether this association with CP, and potentially one with emotional problems (EMOT), is moderated by variants within three genes, previously reported to be associated with ADHD and to moderate the impact of environmental risks on conduct and/or emotional problems; namely, the dopamine transporter gene (SLC6A3/DAT1), the dopamine D4 receptor gene (DRD4) and the serotonin transporter gene (SLC6A4/5HTT).

Methods: We studied 728 males between the ages of 5 and 17 with a DSM-IV research diagnosis of combined type ADHD. Parents and teachers rated children’s conduct and emotional problems. Positive maternal expressed emotion (PMEE) was coded by independent observers on comments made during a clinical assessment with the mother based on current or recent medication-free periods.

1 - Sensitivity to the effects of PMEE on CP was moderated by variants of the DAT1 and 5HTT genes.

2 - Only children who did not carry the DAT1 10R/10R or the 5HTT l/l genotypes showed altered levels of CP when exposed to PMEE.

3 - The effect was most marked where the child with ADHD had both these genotypes.

4 - For EMOT, sensitivity to PMEE was found only with those who carried the DAT1 9R/9R.

4 - There was no effect of DRD4 on CP or EMOT.

Discussion: The gene-environment interactions observed suggested that the genetic make-up can alter the degree of sensitivity that ADHD patients have to their family environment. Further research should focus on distinguishing "general sensitivity genotypes" from those conferring risk or protection.

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