Article by Robert Bucelli, MD, PhD
Biomarkers are measures reflective of biological processes that occur in the body. In the setting of disease, biomarkers may be used for diagnostic, prognostic or treatment monitoring purposes. Phosphorylated neurofilament heavy chain (pNFH) and neurofilament light chain (NFL) are proteins that play an important role in nerve cell function. Both of these proteins are easily measured in blood and cerebrospinal fluid (CSF) and are established markers of nerve cell injury. Studies performed in recent years have demonstrated the utility of these proteins as diagnostic biomarkers in patients with ALS, i.e., these proteins can discriminate between ALS and disease mimics. Additional studies have shown that both markers correlate with rate of disease progression. Accordingly, in early 2019 the Washington University Neuromuscular Laboratory started offering clinical testing for measurement of pNFH values in cerebrospinal fluid and, more recently, serum. Testing for additional biomarkers, including NFL, may also be made available in the future. Serum and CSF pNFH testing may be particularly helpful to physicians caring for patients with “atypical” forms of ALS and will likely play an important role in measuring treatment response as additional therapeutic interventions for ALS are identified.