Neurofilament light chain (NfL), which reflects non-specific axonal damage, exhibits higher concentration levels in PSP than both healthy controls and PD subjects.42 Magdalinou et al.45 reported that NfL levels could differentiate PSP (median levels of 2219 ng/L) from healthy controls (560 ng/L), PD (966 ng/L) and multiple system atrophy (3024 ng/L). The gene discussed is NEFL; the disease is Parkinson disease.