In a separate study comparing PD patients with G2019S-LRRK2 mutations, asymptomatic family members with or without G2019S mutations, patients with idiopathic PD, and non-PD controls, patients with PD had significantly lower levels of urate in their blood than non-PD controls or asymptomatic LRRK2 mutation carriers [11], a result later validated by a larger study [24]. This evidence concerns the gene LRRK2 and Parkinson disease.