Coding and Noncoding Variation in LRRK2 and Parkinson's Disease Risk

Area of Science:

• Genetics
• Neuroscience
• Epidemiology

Background:

• The leucine-rich repeat kinase 2 (LRRK2) gene is implicated in Parkinson's disease (PD) risk.
• Both rare missense variants (e.g., p.G2019S) and common noncoding variants (e.g., rs76904798) are associated with PD.
• Understanding the independent contributions of these variants is crucial for PD research.

Purpose of the Study:

• To determine if the LRRK2 GWAS signal (rs76904798) is independently associated with PD risk, separate from LRRK2 coding variation.
• To investigate if linkage disequilibrium explains the association of LRRK2 coding variants with PD.
• To clarify the role of LRRK2 coding variation in PD etiology.

Main Methods:

• A large meta-analysis of imputed genotypes from over 200,000 individuals (patients and controls) of European ancestry was performed.
• Exclusion criteria were applied to carriers of specific LRRK2 variants (p.G2019S, rs76904798, rare coding variants) to assess independence.
• Co-inheritance patterns of LRRK2 coding variants with p.G2019S and rs76904798 were investigated.

Main Results:

• The LRRK2 variant rs76904798 remained significantly associated with PD risk even after excluding carriers of rare LRRK2 coding variants.
• Specific LRRK2 variants (p.R1514Q and p.N2081D) showed frequent co-inheritance with rs76904798.
• The allele distribution of p.S1647T was significantly altered in PD patients after accounting for rs76904798.

Conclusions:

• LRRK2 coding variants previously linked to PD do not appear to drive the 5' noncoding GWAS signal.
• The findings do not rule out an independent association of certain haplotypes (p.N551K-p.R1398H, p.M1646T) with altered PD risk.
• This study provides insights into the complex genetic architecture of LRRK2 in Parkinson's disease.