From the perspective of linkage in impulsivity and opioid receptor genes, the OPRM1 variant rs1799971 has shown association with impulsivity26; moreover, OPRM1 ‐knockout mice exhibited a marked reduction in motor impulsivity.27 In addition, the occurrence of impulsivity in patients with Parkinson's disease receiving dopamine replacement therapy is known to be related to OPRK1 genotypes28; however, evidence of a relationship between opioid receptor genes and impulsivity is still lacking. The gene discussed is OPRM1; the disease is Parkinson disease.