Multiple system atrophy (MSA) is a rare, progressive neurodegenerative disorder with high mortality and diagnostic uncertainty. We re-evaluated 80 cases from the Catalan MSA Registry (CMSAR), applying the 2022 MDS diagnostic criteria and cerebrospinal fluid biomarkers, including α-synuclein seeding assays (asyn-SAA) and neurofilament light chain (NfL). Clinical and biomarker reassessment was performed in 2022-2023. At re-evaluation, 20 patients were alive; 14 were reclassified as non-MSA and three as unclassifiable. MSA cases had shorter survival (8.8 vs 14.8 years, p = 0.001), and dysphagia predicted poorer outcomes. The 2022 criteria showed higher specificity (94% for clinically established, 71% for probable) than the 2008 criteria. NfL levels were significantly higher in MSA (p = 0.005) and predicted mortality. Asyn-SAA was negative in confirmed MSA cases and positive in three suspected Parkinson's disease cases. These findings support the added diagnostic value of integrating updated criteria and CSF biomarkers to improve MSA classification and long-term monitoring.
Parkinson's disease (PD) is the fastest growing neurodegenerative disorder. The current lack of efficient early diagnostic tools necessitates novel approaches to biomarker discovery. We propose an untargeted metabolomics approach using non-invasive exhaled breath analysis. Breath samples, collected from 73 PD patients, encompassing both genetic (LRRK2: n = 12, GBA1: n = 35, PRKN: n = 6) and idiopathic PD (n = 20), 4 unaffected LRRK2 pathogenic variant carriers, and 90 controls underwent extreme-resolution FT-ICR-MS analysis. Findings were compared with metabolomics data from blood plasma. Biostatistical analyses identified discernible metabolic patterns in both biofluids, enabling differentiation of PD patients from healthy controls (OOB error < 1%). Metabolomic breath profiling of PD patients yielded 7 significant metabolites putatively identified as tricosanoic acid, docosanamide, eicosanoic acid, homophytanic acid, nonadecyl-MG, stearic acid, and palmitic acid in PD patients, irrespective of the genetic status. Five of these metabolites were also found in unaffected carriers of pathogenic variants in LRRK2 when compared to controls. Most of the proposed structures are intermediates in fatty acid metabolism, introducing new candidate biomarkers for breath analysis in PD, although their identities require MS/MS confirmation. Breath analysis effectively distinguishes between PD patients and healthy controls and can identify metabolites that could serve as noninvasive biomarkers for PD, potentially including its presymptomatic stage.

