The eleven-month-old baby from Colchester, identified as Edward, has severe spinal muscular atrophy (SMA) — which means he lacked a protein vital for his muscle development.
SMA is a genetic disease affecting the central nervous system, peripheral nervous system, and voluntary muscle movement (skeletal muscle).
Zolgensma is thought to be the most expensive drug, although NHS England was said to have negotiated an undisclosed discount on its £1.79m list price.
Speaking on the baby’s reception of the drug, which contains a replica of the missing gene SMN1, Megan Willis, Edward’s mother, said she was so relieved and thankful.
Willis was quoted as saying it was “so stressful knowing there was a wonder drug out there” but they could not get hold of it.
She said they had tried to raise the money privately and had started to organise a protest before it was granted.
It is understood that babies born with type 1 SMA, which is the most common form, experience progressive muscle weakness, loss of movement, difficulty breathing, and have a life expectancy of two years.