However, a recent study (49) found that serum profilin-1 concentrations in patients with SMA decreased significantly during the first 2 months of nusinersen treatment; during the maintenance phase, profilin-1 decreased by 14.7% per month, eventually reaching levels similar to those of healthy controls after 26 months of treatment. This evidence concerns the gene PFN1 and proximal spinal muscular atrophy.