The association of the COMT rs4818 G allele and COMT CpG51.52
methylation with the motor impulsivity symptom in MAUD patients.
The relationships of the 8 SNPs in the DRD4 and COMT genes with the
motor impulsive symptoms in MAUD patients were also investigated. The
Mann-Whitney U nonparametric test revealed that there were statistically
significant differences in motor impulsivity scores between COMT rs4818
genotypes (Table 3). Patients carrying the minor alleles had
significantly higher motor impulsivity scores (GG and CG, 42.61) than
patients with the major allele (CC, 36.89) (z=-2.271, p=0.023, Figure
2A), indicating that the G allele carriers were more impulsive in this
study. As shown in Figure 2B, there was a significant difference in the
methylation level in the promoter region of COMT gene between MAUD
patients carrying the minor allele (CG and GG) and the major allele
(CC), and this difference was identified to the methylation degree of
the CpG51.52 unit (Figure 2B, C, p=0.035 & p=0.023, respectively).
Neither the methylation level of COMT nor the methylation degrees at the
CpG 51.52 unit of the COMT gene had a correlation with motor impulsivity
score among MAUD patients (Figure 2D, E). Depending on the COMT rs4818
CC polymorphism, there were negative correlations between COMT
methylation status and motor impulsivity scores in MAUD patients (r=
-0.315, p=0.011) (Figure 2F). However, as shown in Figure 2G showed
that, depending on COMT polymorphism, there was a weak correlation
between the degree of methylation of the CpG51.52 unit at the promoter
region of the COMT gene and the motor impulsivity score (r= -0.268,
p=0.042). The results indicated that the interaction of the COMT rs4818
G allele and COMT methylation status was associated with motor
impulsivity symptom prevalence in MAUD patients.