No Association Between the LRRK2 G2019S Mutation and Alzheimer’s disease in Italy

The LRRK2 R1628P variant plays a protective role in Han Chinese population with Alzheimer's disease

AIMS

Alzheimer's disease (AD) and Parkinson's disease (PD) are the most prevalent neurodegenerative disorders that may share some overlapping etiologies. Mutations within leucine-rich repeat kinase 2 (LRRK2) have been reported to be responsible for PD, and the location of LRRK2 is within a linkage peak for sporadic AD (SAD). The aim of this study was to investigate two Asian-specific LRRK2 variants, R1628P and G2385R, with the association of Han Chinese SAD.

METHODS

Genotyping of R1628P and G2385R was performed by PCR-restriction fragment length polymorphism (RFLP) analysis in 390 patients with SAD and 545 unrelated age- and sex-matched healthy controls.

RESULTS

The frequency of the C allele within R1628P was more than three times higher in control group (1.7%) than in patients with SAD (0.5%) (OR 0.264; 95% CI, 0.088-0.792, P = 0.018). After stratification by the presence of one or two apolipoprotein E ε4 alleles, the protective effect becomes stronger (ε44: OR 0.028; 95% CI, 0.003-0.303, P = 0.003; ε4: OR 0.104; 95% CI, 0.013-0.818, P = 0.031). However, no difference was found in G2385R variant.

CONCLUSION

Our study suggested that R1628P variant within LRRK2 plays a protective role in Han Chinese population with SAD and such effect has an interaction with the APOE genotype.

High-resolution DNA melting analysis in clinical research and diagnostics

Among nucleic acid analytical methods, high-resolution melting analysis is gaining more and more attention. High-resolution melting provides simple, homogeneous solutions for variant scanning and genotyping, addressing the needs of today's overburdened laboratories with rapid turnaround times and minimal cost. The flexibility of the technique has allowed it to be adopted by a wide range of disciplines for a variety of applications. In this review we examine the broad use of high-resolution melting analysis, including gene scanning, genotyping (including small amplicon, unlabeled probe and snapback primers), sequence matching and methylation analysis. Four major application arenas are examined to demonstrate the methods and approaches commonly used in particular fields. The appropriate usage of high-resolution melting analysis is discussed in the context of known constraints, such as sample quality and quantity, with a particular focus placed on proper experimental design in order to produce successful results.

LRRK2 variant associated with Alzheimer's disease

Overlapping neurodegenerative pathologies (including Alzheimer's disease, AD) have been described in Parkinson's disease (PD) patients with leucine-rich repeat kinase-2 (LRRK2) mutations. We analyzed a LRRK2 PD (R1628P) risk variant in a group of 885 subjects comprising of AD and controls. The frequency of the R1628P allele was higher in AD compared to controls (3.5% vs. 1.6%, OR 2.3, 95 CI 1.2-4.4, p=0.018). In vitro, the mean percentage of apoptosis and cell death observed for the R1628P transfected human cell lines was higher compared to wild type 21.8 ± 1.9, vs. 17.1 ± 1.3, p<0.05, 30.2 ± 2.2 vs. 25.7 ± 1.3, p<0.05). The LRRK2 R1628P variant increases the risk of AD in our population and our in vitro findings suggest that it is a functional variant and predisposes to apoptosis.

Co-occurrence of sporadic parkinsonism and late-onset Alzheimer's disease in a Brazilian male with the LRRK2 p.G2019S mutation

Mutations in the leucine-rich repeat kinase 2 (LRRK2) gene represent the most common known genetic cause of inherited and idiopathic Parkinson's disease (PD) in different populations. The predicted multifunctionality of LRRK2 product and the pleomorphic pathology associated with LRRK2 mutations place this gene as a potential candidate for other neurodegenerative disorders, mainly Alzheimer's disease (AD). We report a Brazilian male expressing both late-onset AD and slowly progressive parkinsonism signs, and who presented the most frequent LRRK2 mutation (p.G2019S). Although the co-occurrence of PD and AD would be expected occasionally, the shared mechanisms between the two complex disorders are still unclear and are discussed herein. In light of recent findings about the wide role of LRRK2 under normal and pathological conditions, it is tempting to speculate that LRRK2 mutations might play an upstream influence on the etiology of not just PD but also several alpha-synuclein and tau pathologies, including AD.