One study evaluated neurofilament light chain (NFL), a marker of neuroaxonal injury indicating neuroinflammation and planimetric measurement, and found that although the pontine-to-midbrain-diameter ratio differentiates PSP with PD and multiple system atrophy with predominant parkinsonism (MSA-P), the singular assessment of NLR showed significant differences only at the boundaries of PD and APS (Mangesius et al., 2020). This evidence concerns the gene NEFL and Parkinson disease.