The most commonly used
Parkinson's disease (PD) treatment is the replacement of
dopamine by its
levodopa precursor (
l-dopa).
Monoamine oxidase-B (
MAO-B) and
catechol-o-methyl
transferase (COMT) are
enzymes involved in the metabolism and regulation of
dopamine availability. In our study we investigated the possible relation among selected single-nucleotide polymorphisms (SNPs) in the
MAO-B (rs1799836) and COMT (rs4680) genes and the therapeutic response to
levodopa (
l-dopa). A total of 162 Brazilian patients from the Pro-Parkinson service of Clinics Hospital of Pernambuco diagnosed with sporadic PD and treated with
levodopa were enrolled. PD patients were stratified into 2 groups according to the daily
levodopa dose.
MAO-B and COMT SNP genotyping was conducted by polymerase chain reaction-restriction fragment length polymorphism. After multivariate analysis, we observed a significant difference between PD groups for the following variables: sex (P = .02), longer duration of disease (P = .02), longer
levodopa therapy duration (P = .01), younger onset of PD (P = .01), and use of COMT inhibitor (P = .02). We observed that patients carrying
MAO-B (rs1799836) A and AA genotypes and COMT (rs4680) LL genotype suffered more frequently from
levodopa-induced-
dyskinesia. In addition, we found an increased risk of 2.84-fold for male individuals carrying the
MAO-B G allele to be treated with higher doses of
levodopa (P = .04). We concluded that before beginning PD pharmacological treatment, it is important to consider the genetic variants of the
MAO-B and COMT genes and the sex, reinforcing the evidence that sexual dimorphism in the genes related to
dopamine metabolism might affect PD treatment.