Since the identification in 2004 of mutations within the leucine-rich repeat kinase 2 (LRRK2) gene in patients with autosomal, dominantly inherited Parkinson’s disease, this gene has been the focus of research on Parkinson’s disease.¹ Mutations in the LRRK2 gene and especially the common mutation G2019S may account for 1–2% of familial and 3–6% of sporadic cases of Parkinson’s disease, including those of early and late onset.² The LRRK2 gene is situated on chromosome 12p11.2–q13.1 and encodes a large protein named dardarin. Dardarin contains several functional domains, including a leucine-rich repeat domain, WD40, renin–angiotensin system/guanosine triphosphatases and kinase domains. The presence of the leucine-rich repeat and WD40 domains suggests a role in protein–protein interaction. In addition, function was demonstrated kinase for dardarin in vitro.³

Some questions remain about the growing demand of DNA diagnostics and genetic counselling in Parkinson’s disease. Which subpopulation of patients with Parkinson’s disease harbours the highest risk of mutations in the LRRK2 gene? What is the frequency and penetrance of different LRRK2 mutations? Nine exons (exons 19, 24, 25, 29, 31, 34, 35, 38 and 41) of the LRRK2 gene were screened for sequence …