Plasma neurofilament light chain concentration in the inherited peripheral neuropathies

OBJECTIVE: To perform a cross-sectional study to determine whether plasma neurofilament light chain (NfL) concentration is elevated in patients with Charcot-Marie-Tooth disease (CMT) and if it correlates with disease severity. METHODS: Blood samples were collected from 75 patients with CMT and 67 age-matched healthy controls over a 1-year period. Disease severity was measured using the Rasch modified CMT Examination and neuropathy scores. Plasma NfL concentration was measured using an in-house-developed Simoa assay. RESULTS: Plasma NfL concentration was significantly higher in patients with CMT (median 26.0 pg/mL) compared to healthy controls (median 14.6 pg/mL, p < 0.0001) and correlated with disease severity as measured using the Rasch modified CMT examination (r = 0.43, p < 0.0001) and neuropathy (r = 0.37, p = 0.044) scores. Concentrations were also significantly higher when subdividing patients by genetic subtype (CMT1A, SPTLC1, and GJB1) or into demyelinating or axonal forms compared to healthy controls. CONCLUSION: There are currently no validated blood biomarkers for peripheral neuropathy. The significantly raised plasma NfL concentration in patients with CMT and its correlation with disease severity suggest that plasma NfL holds promise as a biomarker of disease activity, not only for inherited neuropathies but for peripheral neuropathy in general.