PINK1 mutation heterozygosity and the risk of Parkinson's disease

Background: Mutations in the PTEN-induced kinase 1 (PINK1) gene have been identified in recessively inherited and sporadic early-onset parkinsonism (EOP). Methods: A total of 131 Norwegian patients diagnosed with Parkinson's disease were included. Of them, 89 participants had EOP (onset <= 50 years); the remaining had familial late-onset disease (mean age at onset 64 years). PINK1 analysis included sequencing and gene dose assessment. Mutations were examined in 350 controls. Results: Heterozygous missense mutations in PINK1 were found in 3 of 131 patients; none of the patients carried homozygous or compound heterozygous mutations. One of these three patients had a father affected by Parkinson's disease, and he carried the mutation. Three new and seven known polymorphic variants were identified, although none seemed to be associated with disease risk. Conclusions: PINK1 mutations are rare in Norwegian patients with EOP and familial Parkinson's disease. However, the data suggest that some heterozygous mutations might increase the risk of developing Parkinson's disease.