Downregulation of HNF4A has been reported in blood from PD patients as a PD biomarker correlating with motor symptoms severity (Potashkin et al, 2012; Santiago & Potashkin, 2015), whereas FOSL2 has been linked to dyskinesia, a major side effect in the DA substitutive treatment with L‐DOPA (Cao et al, 2010). This evidence concerns the gene HNF4A and drug-induced dyskinesia.