NEFL and amyotrophic lateral sclerosis: These results were in accordance with a recent study on the neurofilament light chain (NfL), which included presymptomatic patients at genetic risk for ALS, demonstrating that serum NfL levels were elevated up to 12 months before symptom onset.16 In contrast, it has been reported that asymptomatic mutation carriers had normal serum NfL levels that were not different from non‐mutation carrier controls.15 However, it should be noticed that in the latter study most of samples of the asymptomatic mutation carriers were collected more than 24 months before the onset of symptoms.