Small ubiquitin-related modifier (SUMO) 3 and SUMO4 gene polymorphisms in Parkinson's disease

Objectives: The ubiquitin/proteasome system is one of the main axes of the pathogenesis of Parkinson's disease (PD). Small ubiquitin-related modifier (SUMO) proteins are involved in many biochemical events including regulation of transcriptional activity, modulation of signal transduction pathways, and response to cellular stress indicating a role for SUMO in the ubiquitin/proteasome system.Methods: In this study, our aim was to examine the prevalence of SUMO gene variants and their clinical associations in PD. Fifty-four consecutively recruited PD patients (34 male, 20 female) and 74 age-gender matched healthy controls (37 male, 37 female) were included. SUMO1, 2, 3 and 4 genes were screened by a next generation sequencing method using blood samples of participants. Single nucleotide polymorphisms (SNPs) with a significantly altered prevalence were determined by Bonferroni correction.Results: Two SNPs in the SUMO4 gene (rs237025 and rs237024) and two SNPs in the SUMO3 gene (rs180313 and rs235293) were found to have altered prevalence in PD. Although there was no association among these SNPs and clinical features of the patients, an increased family history of cancer was found in patients with SUMO3 gene variants.Discussion: Several SUMO SNPs were identified for the first time in PD patients suggesting that SUMO is involved in the pathophysiology of the disease. rs237025 has also been associated with diabetes mellitus indicating a pathogenic mechanism for SUMO that is shared with other degenerative disorders.