In 1–2% of PD cases, the cause of PD is attributed to the highly penetrant, autosomal dominant and recessive genes; in 5–10% of PD cases, PD is associated with strong risk genes (e.g. LRRK2 and GBA mutations); and the remaining cases are idiopathic without a single identifiable cause [6]. The gene discussed is LRRK2; the disease is Parkinson disease.