While the difference was not statistically significant, there was a trend toward faster motor decline in participants with α-syn SAA positive LRRK2 PD (n=111; 2.39 (1.86 – 2.92)) compared to those with α-syn SAA negative LRRK2 PD (n=51; 1.76 (0.93 – 2.60); difference=0.63 (−0.29 – 1.55), p=0.18). This evidence concerns the gene LRRK2 and Parkinson disease.