Neurofilament light chain, a biomarker for polyneuropathy in systemic amyloidosis.

OBJECTIVE

To study serum neurofilament light chain (sNfL) in amyloid light chain (AL) amyloidosis patients with and without polyneuropathy (PNP) and to corroborate previous observations that sNfL is increased in hereditary transthyretin-related (ATTRv) amyloidosis patients with PNP.

METHODS

sNfL levels were assessed retrospectively in patients with AL amyloidosis with and without PNP (AL/PNP+ and AL/PNP-, respectively), patients with ATTRv amyloidosis and PNP (ATTRv/PNP+), asymptomatic transthyretin ( gene mutation carriers (v carriers) and healthy controls. Healthy controls (HC) were age- and sex-matched to both AL/PNP- (HC/AL) and v carriers (HC/v). The single-molecule array (Simoa) assay was used to assess sNfL levels.

RESULTS

sNfL levels were increased both in 10 AL/PNP+ patients ( < .001) and in 10 AL/PNP- patients ( < .005) compared to 10 HC/AL individuals. sNfL levels were higher in AL/PNP+ patients than in AL/PNP- patients ( < .005). sNfL levels were also increased in 15 ATTRv/PNP+ patients, compared to both 15 HC/v ( < .0001) and 15 v carriers ( < .0001). ATTRv/PNP+ patients with progressive PNP (PND-score > I) had the highest sNfL levels compared to patients with early PNP (PND-score I) ( = .05). sNfL levels did not differ between v carriers and HC/v individuals. In the group comprising all healthy controls and in the group of v carriers, sNfL levels correlated with age.

CONCLUSION

sNfL levels are increased in patients with PNP in both AL and ATTRv amyloidosis and are related to severity of PNP in ATTRv amyloidosis. sNfL is a promising biomarker to detect PNP, not only in ATTRv but also in AL amyloidosis.