First Clinicogenetic Description of Parkinson's Disease Related to GBA Mutation S107L

Background Mutations in the glucocerebrosidase gene (GBA) are a common genetic risk factor for Parkinson's disease (PD). Mutations in the N-terminus part of GBA are less commonly found in association with PD than those in the C-terminus. Phenotypic characterization of GBA-related PD has been challenging, in part attributed to differential impact of distinct GBA mutations. Aim To provide a phenotypic description of two patients with PD heterozygous for the GBA mutation S107L. The S107L mutation is located in the catalytic domain of glucocerebrosidase and has not previously been reported in patients with PD. Methods Motor and nonmotor symptoms (NMS) of PD were evaluated using established rating scales and questionnaires. The genotype was determined by Sanger sequencing. Results Two half-brothers, both heterozygous carriers of S107L, exhibited an early PD onset with several NMS. Conclusions In these patients, heterozygosity for S107L was associated with an early onset of PD with NMS.