Of 133 referrals, 93 patients were diagnosed with amyotrophic lateral sclerosis (median neurofilament light chain 218.1 pg/ml, interquartile range 130.7–311.9), three primary lateral sclerosis (65.6, 51.5–106.9) and 19 alternative diagnoses (45.2, 13.5–71.9) at first visit. This evidence concerns the gene NEFL and amyotrophic lateral sclerosis.