SMN1 and proximal spinal muscular atrophy: Thus, immortalized skeletal muscles cells obtained from an 11‐year‐old SMA patient (0 SMN1 and 3 SMN2 copies) were differentiated for 4 days (D4) and then incubated with either the vehicle (Veh) or varying doses of UA (25, 50 or 100 μM) for a 24‐h period (Figure 8A).