NEFL and polyneuropathy: Patients with ATTRv polyneuropathy had higher levels of serum NfL than healthy controls (16 vs. 69.4 pg/mL, respectively), and after 18 months, serum NfL levels increased with placebo (36.3 mg/mL increase) and decreased with transthyretin (TTR) silencer patisiran treatment (-23.3 pg/mL), correlating with clinical progression in the placebo group versus the treatment group30.