Supplementary Material for: Genetic Variations in the Dopamine System and Facial Expression Recognition in Healthy Chinese College Students

<i>Objective:</i> This study investigated the relation between genetic variations in the dopamine system and facial expression recognition. <i>Methods:</i> A sample of Chinese college students (n = 478) was given a facial expression recognition task. Subjects were genotyped for 98 loci [96 single-nucleotide polymorphisms (SNPs) and 2 variable number tandem repeats] in 16 genes involved in the dopamine neurotransmitter system, including its 4 subsystems: synthesis<i> (TH, DDC,</i> and <i>DBH)</i>, degradation/transport <i>(COMT,</i><i>MAOA,</i><i>MAOB,</i> and <i>SLC6A3)</i>, receptors<i> (DRD1,</i><i>DRD2,</i><i>DRD3,</i><i>DRD4,</i> and <i>DRD5)</i>, and modulation <i>(NTS,</i><i>NTSR1,</i><i>NTSR2,</i> and <i>NLN)</i>. To quantify the total contributions of the dopamine system to emotion recognition, we used a series of multiple regression models. Permutation analyses were performed to assess the posterior probabilities of obtaining such results. <i>Results:</i> Among the 78 loci that were included in the final analyses (after excluding 12 SNPs that were in high linkage disequilibrium and 8 that were not in Hardy-Weinberg equilibrium), 1 (for fear), 3 (for sadness), 5 (for anger), 13 (for surprise), and 15 (for disgust) loci exhibited main effects on the recognition of facial expressions. Genetic variations in the dopamine system accounted for 3% for fear, 6% for sadness, 7% for anger, 10% for surprise, and 18% for disgust, with the latter surviving a stringent permutation test. <i>Conclusions:</i> Genetic variations in the dopamine system (especially the dopamine synthesis and modulation subsystems) made significant contributions to individual differences in the recognition of disgust faces.