Quantification of the Light Subunit of Neurofilament Protein in Cerebrospinal Fluid of Huntington's Disease Patients

Neurofilament light proteins (NFL) are a structural element of the neuronal cytoskeleton and are released with neuronal damage. Its levels are increased in cerebrospinal fluid (CSF) in the setting of neurodegenerative diseases. We investigated the CSF-NFL levels of Huntington´s disease (HD) patients (participating in a clinical trial SAT-HD) as well as of premanifest carriers and compared their results with a sample of healthy controls and correlated CSF-NFL levels with demographic and clinical variables (baseline demographic characteristics and HD measures of disease severity). CSF levels were significantly higher in all HD subjects [5014.4 (1557.3) ng/l] and pre-manifest carriers [1050 (212.13) ng/l as compared to controls [331.4 (200.2) ng/l] (p<0.00) and were correlated with age (correlation coefficient -0.37, p<0.01) and CAG triplet number (0,51, p<0.05) in the subset of HD patients. NFL levels were not correlated with age in the control group. We did not find any correlation with the remaining variables. These results indicate, as in previous studies, that CSF-NFL levels are a marker of neuronal damage in HD. It seems to be a highly sensitive, but non-specific marker of axonal damage. One of the limitations of our study is a very small number of patients in pre-symptomatic group and lack of individuals with very advanced HD. Further investigations should focus on study of CSF-NFL levels in advanced patients, tracking prospectively CSF-NFL levels and analysing its correlation with the clinical course and usefulness to monitor disease progression, validation and quantification of NFL levels in more accessible biofluids.