When Oscar was just over three weeks old he received a £1.8m single dose of gene therapy Zolgensma – the most expensive drug in the world.
But before the drug was made available, children with this SMA Type 1 typically survived less than two years, according to the NHS, external.
Now aged three, Oscar loves cars, singing, playing with his sister Edie and little brother Finn, and Paw Patrol.
But Kayleigh said he needs a feeding tube, other equipment to assist his breathing and lung function, and a frame to stand up.
Kayleigh, 38, also said as her son gets bigger the family will have to “fund significant house adaptations”.
She said early diagnosis of the condition, through a heel-prick blood test that can be used to pick up SMA Type 1, was key.
“If it wasn’t for the medical staff at the hospital, who we are very grateful to, we would have taken Oscar home and watched him decline even further – which is the experience of many families,” she said.
“And he has gone on to start speaking, which is something we were not sure would happen.”