Interestingly, another study in a heterogeneous population of SMA type 1–3 patients younger than 18 years old found a decrease in total tau (but not in NF-L) levels in CSF [45], suggesting that tau CSF levels might be more useful than NF-L to measure nusinersen response in pediatric forms and older children. The gene discussed is NEFL; the disease is spinal muscular atrophy, type 1.