Meta-analysis of brain iron levels of Parkinson's disease patients determined by postmortem and MRI measurements.

Brain iron levels in patients of Parkinson's disease (PD) are usually measured in postmortem samples or by MRI imaging including R2* and SWI. In this study we performed a meta-analysis to understand PD-associated iron changes in various brain regions, and to evaluate the accuracy of MRI detections comparing with postmortem results. Databases including Medline, Web of Science, CENTRAL and Embase were searched up to 19th November 2015. Ten brain regions were identified for analysis based on data extracted from thirty-three-articles. An increase in iron levels in substantia nigra of PD patients by postmortem, R2* or SWI measurements was observed. The postmortem and SWI measurements also suggested significant iron accumulation in putamen. Increased iron deposition was found in red nucleus as determined by both R2* and SWI, whereas no data were available in postmortem samples. Based on SWI, iron levels were increased significantly in the nucleus caudatus and globus pallidus. Of note, the analysis might be biased towards advanced disease and that the precise stage at which regions become involved could not be ascertained. Our analysis provides an overview of iron deposition in multiple brain regions of PD patients, and a comparison of outcomes from different methods detecting levels of iron.

The RIT2 and STX1B polymorphisms are associated with Parkinson's disease.

INTRODUCTION: GWAS meta-analysis identified RIT2 rs12456492 and STX1B rs4889603 as PD susceptible loci. While proteins encoded by the genes, in particular RIT2, may involve in PD pathogenesis, the association of these two variants with PD remains to be further clarified. METHODS: We enrolled a Chinese cohort comprising 537 PD patients and 517 controls, determined the genotypes of rs12456492 and rs4889603, and analyzed these variants in relation to PD. RESULTS: Both rs12456492 and rs4889603 were associated with PD susceptibility (P = 0.012 and 0.03, respectively). The G allele of rs12456492 and the A allele of rs4889603 served as risk alleles toward PD. Statistical differences in genotype distribution between the patients and controls were observed both in rs12456492 (marginal, P = 0.042 for GG vs. AG vs. AA) and in rs4889603 (P = 0.021 for AA + AG vs. GG) CONCLUSION: Our data suggest that the RIT2 and STX1B polymorphisms are associated with PD etiology. The role of RIT2 in PD pathogenesis warrants further mechanistical investigation.