BDNF and Parkinson disease: The frequencies of DAT and COMT genotypes displayed HWE in both PD groups (p > .05) while the distribution of BDNF genotypes showed significant deviation from HWE also in both PD groups (p = .001 and p = .009, respectively) (Table 4) and in MLIC subgroups (patients with only on‐off phenomena and patients with both on‐off phenomena and dyskinesias: p = .016 and p = .018, respectively) as well.