Recent studies by Yu et al. have shown the detrimental effect of single nucleotide polymorphism (SNP) of catechol-o-methyltransferase (COMT)—COMT rs4680 SNP on the motor symptoms of PD patients, as well as the authors found that ALDH2 rs671 SNP moderated the impact of COMT rs4680 (A) for the symptom of ‘hand movements’ [23]. This evidence concerns the gene ALDH2 and Parkinson disease.