However, the substitution of the serine residue by a glycine residue in exon 41 of the protein kinase domain in LRRK2 (G2019S mutation) is the most common mutation across 51 countries [13], accounting for 1% of sporadic PD cases and 4% of familial PD cases, among all cases [14,15]. Here, LRRK2 is linked to Parkinson disease.