No abstract

Background: Earlier studies reported alterations of the kynurenine (KYN) pathway of tryptophan (TRP) metabolism in Parkinson's disease (PD). The first rate-limiting enzymes indoleamine 2,3-dioxygenase (IDO) and tryptophan dioxygenase were observed upregulated, resulting elevated KYN/TRP ratios in the serum and cerebrospinal fluid samples of patients with PD. More and more single nucleotide polymorphisms (SNPs) have been identified in a population of PD. However, little is known about the impact of genetic variations of the IDO on the pathogenesis of PD. Methods: SNP analysis of IDO1 was performed by allelic discrimination assay with fluorescently labelled TaqMan probes and a subgroup analysis was conducted according to the age of PD onset. The frame shifts variant rs34155785, intronic variant rs7820268, and promotor region variant rs9657182 SNPs of 105 PD patients without comorbidity were analyzed and compared to 129 healthy controls. Results: No significant correlation was found in three SNPs between PD patients and healthy controls. However, the subgroup analysis revealed that A alleles of rs7820268 SNP or rs9657182 SNP carriers contribute to later onset of PD than non-carriers. Conclusions: The study suggested that SNPs of IDO1 influenced the age onset of PD and genotyping of SNPs in certain alleles potentially serves as a risk biomarker of PD.

Parkinson’s disease (PD) is a neurodegenerative disease caused by complex interaction between genetic and environmental factors. There is a growing body of evidence of the involvement of sirtuins (SIRTs) in disease pathomechanism. SIRTs are NAD+-dependent histone deacetylases which take part in various cellular functions. However, available data of the relationship between SIRT gene polymorphisms and PD is limited. Our aim was to investigate the possible association of 10 SNPs identified within non-mitochondrial SIRTs, SIRT1, -2 and -6 with the risk of PD in Hungarian population, and to compare the expression level of these SIRTs between healthy controls and PD patients. Our results showed that rs3740051 and rs3818292 of SIRT1 and rs350843, rs350844, rs107251, rs350845 and rs350846 of SIRT6 show weak association with PD risk. On the contrary rs12778366 and rs3758391 of SIRT1 and rs10410544 of SIRT2 did not show association with PD. Moreover, we detected that mRNA level of SIRT1 was down-regulated, and mRNA level of SIRT6 was up-regulated, while SIRT2 mRNA level was not altered in the peripheral blood of PD patients as compared to controls. The difference in both cases was more pronounced when comparing the early-onset PD group to the control cohort. Nevertheless, mRNA level changes did not show any association with the presence of any of the investigated SNPs either in the PD or in the control group. In conclusion, our findings suggest that non-mitochondrial sirtuins, SIRT1 and -6 but not SIRT2 might contribute to the pathogenesis of PD in the Hungarian population both via their altered mRNA levels and via gene alterations identified as specific SNPs.

Earlier studies reported alterations of the kynurenine (KYN) pathway of tryptophan (TRP) metabolism in Parkinson’s disease (PD). The first rate-limiting enzymes indoleamine 2,3-dioxygenase (IDO) and tryptophan dioxygenase were observed upregulated, resulting elevated KYN/TRP ratios in the serum and cerebrospinal fluid samples of patients with PD. An increasing number of single nucleotide polymorphisms (SNPs) have been identified in a population of PD. However, little is known if genetic variations of the IDO contribute to disturbance of the KYN metabolism in and the pathogenesis of PD. SNP analysis of IDO1 was performed by allelic discrimination assay with fluorescently labelled TaqMan probes and a subgroup analysis was conducted according to the age of PD onset. The frame shifts variant rs34155785, intronic variant rs7820268, and promotor region variant rs9657182 SNPs of 105 PD patients without comorbidity were analyzed and compared to 129 healthy controls. No significant correlation was found in three SNPs between PD patients and healthy controls. However, the subgroup analysis revealed that A alleles of rs7820268 SNP or rs9657182 SNP carriers contribute to later onset of PD than non-carriers. The study suggested that SNPs of IDO1 influenced the age onset of PD and genotyping of SNPs in certain alleles potentially serves as a risk biomarker of PD.