copy of a missing, orfaulty, gene called smni. this is inserted into a harmless virus. in the body, the virus delivers the replacement gene into the nucleus of motor neuron cells. this is essential to prevent those cells from gradually dying. the now healthy motor neuron cells start producing the missing smni protein, which is vital for muscle function. how s arthur? evelina london children s hospital is one of a handful of centres in the uk which will offer this ground breaking gene therapy. i think it has the potential to make a very significant difference, to enable children to acquire motor skills such as rolling and sitting, that would have been impossible without treatment for sma. she was really floppy. she couldn t sit, - she couldn t hold toys. she couldn t do anything. tora received zolgensma in the us nearly two years ago.