The levels of blood NfL were clearly increased in PSP, MSA, and CBS when compared to controls (PSP, p < 0.001; MSA, p < 0.001; CBS, p < 0.001) and patients with PD (PSP, p = 0.001; MSA, p < 0.001; CBS, p < 0.001). This evidence concerns the gene NEFL and Parkinson disease.