rarely live beyond the age of two. arthur is unable to lift his head and struggles to move his arms and legs. but this single infusion should prevent further loss of nerve cells. it's been massive ups and downs, but being able to now have the treatment is just going to be a game changerfor us, and give arthur the best possible life he could have. around one in every 10,000 babies is born with spinal muscular atrophy. what is remarkable is this one—off treatment may permanently stop any further decline in arthur's muscle function. so, how does zolgensma work? it contains a healthy copy of a missing or faulty gene called smn1. 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