Mutations in the leucine-rich repeat kinase 2 gene (LRRK2), located at 12q12, are the most common known genetic causes of Parkinson’s disease (PD). Studies of LRRK2 mutation carriers have shown incomplete and age-dependent penetrance and previous studies have suggested that inherited susceptibility factors may modify the penetrance of LRRK2 mutations.

Genomewide linkage to age of onset of LRRK2-related PD was evaluated in a sample of 113 LRRK2 mutation carriers from 64 families using single nucleotide polymorphism data from the Illumina HumanCNV370 genotyping array. Association between onset age and SNPs located under suggestive linkage peaks was also evaluated.

The top LOD-score for onset age (LOD-score=2.43) was located in the chromosome 1q32.1 region. Moderate linkage to onset was also identified at 16q12.1 (LOD-score=1.58). Examination of single nucleotide polymorphism association to PD onset under the linkage peaks revealed no statistically significant SNP associations.

The two novel genomic regions identified may harbor modifiers of LRRK2-related PD onset age or penetrance and further study of these regions may provide important insight into LRRK2-related PD.