The addiction-related gene ANKK1 in Parkinsonian patients with impulse control disorder

Impulse control disorders (ICDs) comprise a wide spectrum of abnormal behaviors frequently found in patients with Parkinson's disease (PD) receiving antiparkinsonian treatment. Some ICDs share several essential features with substance use disorders. In this work, we have studied the addiction-related gene ankyrin repeat and kinase domain containing I (ANKK1) in a sample of PD patients involved in a multicenter study on ICD. We carried out the TaqIA ANKK1 single-nucleotide polymorphism (SNP) genotyping in PD patients. Clinical assessment of ICD was performed using the Questionnaire for impulsive-compulsive disorders in PD. We found no association between TaqIA SNP and ICD in PD patients (p = 0.565). However, when PD patients were grouped according the diagnosis of any ICD with a potentially addictive reinforcement (ICDARs), A1- TaqIA genotype showed significant association (p = 0.036). No association was found for the presence of punding in PD patients (p = 0.289). A logistic regression analysis confirmed the independent effect of the A1- genotype upon ICDARs (OR 8.76, 95 % CI 1.3-57.8, Wald = 5.805, p = 0.024). The TaqIA genotype A1- is associated to ICDAR in our sample and it may differentiate two types of disorders which are part of the ICD definition in PD patients.