In this group of TTRv carriers who developed polyneuropathy, the median baseline serum NfL level of 8.4 pg/mL rose to a median of 49.8 pg/mL upon the onset of initial symptoms (PND I), and the serum NfL level had risen even further at the time polyneuropathy could be established by nerve-conduction studies. The gene discussed is NEFL; the disease is polyneuropathy.