Association Between Catechol-O-Methyltransferase (COMT) Gene Polymorphisms, Parkinson's Disease, and Levodopa...

We investigated the association between catechol-O-methyltransferase (COMT) gene polymorphisms and Parkinson's disease (PD) susceptibility, severity of disease, and levodopa (L-Dopa) efficacy.

Patients (N = 97) with primary PD and healthy volunteers (N = 102) were recruited. Disease severity was assessed with the Unified Parkinson's Disease Rating Scale (UPDRS) and Hoehn & Yahr grade at 'On stage'. Genomic DNA was extracted from blood cells. Polymerase chain reaction and sequencing were used to detect COMT mutations. Data were analyzed by SPSS 18.0. False discovery rate (FDR) or Bonferroni correction was used if the result showed P < 0.05.

Four COMT mutations were detected in 199 subjects: rs74745580 (only in two patients with primary PD), rs4633, rs6267, and rs3838146. There were no statistical differences in frequencies of rs4633, rs6267, and rs3838146 genotypes between PD patients and the control group. The frequency of allele rs4633T was higher in PD patients than in the control group. UPDRS score was lower in rs4633 (CT/TT) carriers and rs3838146 (-C/- -) carriers than in rs4633 (CC) and rs3838146 (CC) carriers. PD patients carrying rs6267 (GT/TT) had higher UPDRS scores than patients with rs6267 (GG) (P < 0.05). The frequencies of the three polymorphisms were not statistically different between patients who did and did not receive L-Dopa; dose and duration of L-Dopa treatment did not differ between genotypes; and there was also no difference in the ratios of loss of efficacy towards levodopa.

The polymorphisms rs4633, rs6267, and rs3838146 were associated with severity of PD but were not associated with L-Dopa medication.