Association of serum neurofilament light (sNfL) and disease severity in patients with spinocerebellar ataxia type 3

Objective: To investigate serum neurofilament light protein (sNfL) levels in patients with spinocerebellar ataxia type 3 (SCA3) and to determine whether they are associated with disease severity.

Methods: This cross-sectional study enrolled 185 healthy controls and 235 ATXN3 mutation carriers (17 asymptomatic stage, 20 preclinical stage, and 198 ataxic stage). We measured sNfL levels with the single molecule array (Simoa) platform. Clinical disease severity was assessed using the scale of assessment and rating of ataxia (SARA) and the inventory of non-ataxia signs (INAS). In a subgroup of 50 ataxic stage patients, we further evaluated the gray matter volume and the integrity of white matter fibers by magnetic resonance imaging (MRI).

Results: sNfL concentrations were elevated in asymptomatic, preclinical, and ataxic ATXN3 mutation carriers compared to controls (12.18 [10.20-13.92], 21.84 [18.37-23.45], 36.06 [30.04-45.90] and 8.24 [5.92-10.84] pg/mL, median [interquartile range], ...