NEFH and amyotrophic lateral sclerosis: The phosphorylation of NF-H and NF-M is believed to be involved in regulating interfilament spacing and axonal caliber.15 Phosphorylated NF-H (pNF-H) mediates interactions with other cytoskeletal elements, particularly microtubules.16 Abnormally phosphorylated NFs in the cell bodies have been proposed to be the common feature of neurodegenerative diseases, such as amyotrophic lateral sclerosis and Alzheimer disease.16 Of the various NFs, pNF-H is relatively resistant to proteolysis,17 so it was less likely to be degraded in blood than the other NFs.