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Exome Sequencing Reveals Signal Transduction Genes Involved in Impulse Control Disorders in Parkinson's Disease

Year: 2020

Type: article

Abstract: Introduction: Impulse control disorders (ICDs) frequently complicate dopamine agonist (DA) therapy in Parkinson’s disease (PD). There are growing evidence of a high heritability for ICDs in the general population and in PD. Variants on genes belonging to the reward pathway have been shown to account for part of this heritability. We aimed to identify new pathways associated with ICDs in PD. Methods: Thirty-six parkinsonian patients on DA therapy with (n=18) and without ICDs (n=18) matched on age at PD’s onset and gender were selected to represent the most extreme phenotypes of their category. Exome sequencing was performed and variants with a strong functional impact in brain-expressed genes were selected. Allele frequencies and their distribution in genes and pathways were analyzed with single variant and SKAT-O tests. The 10 most associated variants, genes and pathways were retained for replication in the Parkinson’s Progression Markers Initiative (PPMI) cohort. Results: None of markers tested passed the significance threshold adjusted for multiple comparisons. However, the “Adenylate cyclase activating” pathway, one of the top associated pathway in the discovery dataset (p=1.6×10-3) was replicated in the PPMI cohort, and was significantly associated with ICDs in a post-hoc pooled analysis (combined p-value 3.3×10-5). Two of the ten most associated variants belonged to genes implicated in cAMP and ERK signaling (rs34193571 in RasGRF2, p=5×10-4; rs1877652 in PDE2A, p=8×10-4) although non-significant after Bonferroni correction. Conclusion: Our results suggest that genes implicated in the signaling pathways linked to G protein-coupled receptors participate to genetic susceptibility to ICDs in PD. These results are in accordance with the importance of ERK and cAMP signaling pathways in the dopamine-dependent plasticity in the striatum.

Source: Frontiers in Neurology

DOI: 10.3389/fneur.2020.00641