NfL protein in blood may help track myasthenia gravis severity: Study
Potential biomarker could complement existing clinical, serological tools
People with myasthenia gravis (MG) have higher levels of a protein called neurofilament light chain (NfL) in their blood, especially if their symptoms are severe or start later in life, a recent study found.
This means that NfL could help doctors track how the disease develops and decide on treatment. “As a readily measurable” biomarker, NfL “could complement existing clinical and serological tools,” researchers wrote.
The study, “Serum neurofilament light chain levels in myasthenia gravis patients with and without symptoms,” was published in Frontiers in Medicine.
Median levels of NfL protein in blood higher in patients than in controls
MG is a disease where the immune system interferes with the communication between nerves and muscles, causing weakness and fatigue.
In this study, researchers in China looked at whether NfL, a biomarker of nerve damage, could help doctors better understand and classify MG.
“In MG, [blood NfL] may reflect the degree of neuromuscular junction damage and neuronal stress, particularly in subgroups where traditional biomarkers … may be less informative,” the researchers wrote. “It is rational to hypothesize that NFL levels may be elevated in MG and that this measurement could be beneficial for disease monitoring.”
Their study included 60 patients — 28 with ocular MG and 32 with generalized MG — and 29 healthy controls. Both groups were similar in terms of age and sex.
The median levels of NfL in the blood were significantly higher in patients than in controls (12.7 picograms per milliliter or pg/mL vs. 9.1 pg/mL ), suggesting they may signify disease.
The Quantitative Myasthenia Gravis (QMG) score, which ranges from 0 (no muscle weakness) to 39 (severe muscle weakness), was no higher than 6 for 28 patients. The other 30 patients had a score of 7 to 15, indicating moderate muscle weakness. Patients with higher QMG scores also had higher NfL levels (13.4 pg/mL vs. 6.9 pg/mL).
In conclusion, [blood NfL] levels are elevated in MG patients, particularly in severe and late-onset cases, suggesting its potential as a biomarker for disease stratification and severity assessment.
According to the MG Foundation of America (MGFA) classification, 32 patients had ocular symptoms only (Class I), 12 had mild generalized weakness primarily affecting the limbs (Class IIa), and another 12 had mild generalized weakness primarily affecting respiratory muscles, or those in the mouth and throat (Class IIb).
Patients with MGFA Class IIb had significantly higher levels of NfL in the blood compared with controls. For those with MGFA Class I and Class IIa, the difference was not significant. This suggests that NfL may increase more as the disease becomes more severe or affects a larger number of muscles.
Age at the time of disease onset also affected the levels of this biomarker. Patients with late-onset MG (after age 50) had significantly higher levels of NfL than those whose disease began earlier, known as early-onset MG. For patients with late-onset MG, NfL was highly accurate at diagnosing the disease.
“In conclusion, [blood NfL] levels are elevated in MG patients, particularly in severe and late-onset cases, suggesting its potential as a biomarker for disease stratification and severity assessment,” the researchers wrote.
About the Author
