NEFL and proximal spinal muscular atrophy: With the development of the anti-oligonucleotide (ASO) Nusinersen, there are studies where both neurofilament light chain (pNf-L), using ultrasensitive single molecule matrix technology Simoa® (Single Molecule Array), manufacturer by Quanterix, Billerica, MA, USA., and heavy chain (pNfH), using the ProteinSimple® (Ella immunoassay platform) manufacturer by Bio-echne, San Jose, CA, USA, as well as its correlation with Nf in CSF, have been analyzed in plasma as blood biomarkers in different types of SMA.