Genetic analysis of GBA1 gene in a cohort of patients with Parkinson's disease

Background: Variants in the GBA1 gene, which encodes the lysosomal enzyme glucocerebrosidase (GCase), are among the strongest genetic risk factors for Parkinson's disease (PD). While several pathogenic mutations are well-characterized, the impact of many rare or novel variants remains unclear. Objective: This study is aimed to explore the spectrum of GBA1 variants in a cohort of PD patients from Southern Italy, with a particular focus on the clinical and structural characterization of a novel missense variant through integrated genetic and in silico analyses. Methods: We performed targeted next-generation sequencing (NGS) on 171 PD patients using a custom AmpliSeq panel covering 30 PD-related genes. Structural modelling of identified missense variants was conducted using UCSF ChimeraX (v.1.10) to assess potential conformational changes, while secondary structures were analyzed using the DSSP (Define Secondary Structure of Proteins) algorithm. Energetic impact of the amino acid substitutions on protein stability was evaluated using FoldX (v.4). Results: Ten patients carried likely pathogenic GBA1 variants, including common mutations such as p.L483P, p.N409S, p.E365K, p.H294Q, and p.I200N. A novel heterozygous variant, p.K505N, was identified in a familial PD case and found to co-segregate with the disease in two affected relatives. Conclusion: This study expands the spectrum of GBA1 variants associated with PD and provides structural evidence supporting the potential pathogenicity of the novel p.K505N variant.