Hemoglobin-binding α-synuclein levels in erythrocytes are elevated in patients with multiple system atrophy

Previous studies have shown that α-synuclein (α-syn) accumulation in the normal aging brain is associated with a parallel increase in hemoglobin-binding α-syn (Hb-α-syn) in the brain and peripheral erythrocytes (ERCs), indicating that Hb-α-syn levels in ERCs may reflect the α-syn changes in the brain. However, if there is any change in ERC Hb-α-syn levels in disease condition is unclear. In this study, Hb-α-syn levels in ERCs from 149 Patients with multiple system atrophy (MSA) and 149 healthy controls (HCs) were measured by enzyme linked immunosorbent assay (ELISA). The results showed that Hb-α-syn levels in ERCs were significantly increased in MSA patients in comparison with those in HCs (777.84 ± 240.82 ng/mg vs 508.84 ± 162.57 ng/mg, P < 0.001). Receiver operating characteristic curve (ROC) indicated that increased Hb-α-syn in ERCs could discriminate MSA patients from HCs, with a sensitivity of 71.8%, a specificity of 80.5%, and an area under the curve (AUC) of 0.837. The positive and negative predictive values at a cut-off value of 616.12 ng/mg were 78.7% and 74.1%, respectively. However, the increase in Hb-α-syn levels did not show any association with the age of onset and consultation, disease duration, and UMSARS (I-IV) score. This pilot study suggests that ERC Hb-α-syn is increased in MSA patients and could evaluate α-syn accumulation in the brain of patients.