Violet Revet of Langenburg is one of only nine people in Canada who has Mucopolysaccharidosis VI.
The disease has no cure and the longer she goes without treatment, the shorter her life span will be.
Andrew McFayden's son, Isaac, was diagnosed with the disease in 2005.
McFayden, of Campbellford, Ont., was told Isaac would only have seven or eight years to live.
That was before doctors realized a treatment was making the rounds in the United Kingdom and the United States — a synthetic enzyme known as naglazyme that acts as a replacement in the body.
Isaac could get access to it under a special access program but the drug wasn't covered in Ontario.
It took McFayden eight months of lobbying before the provincial government agreed to pay for it at a cost of about half a million dollars a year.
"It's a very devastating condition," said McFadyen, whose eight-year-old son goes to Toronto for regular treatments.
"Essentially, kids that are diagnosed with (it) lack an enzyme in their blood that breaks down all the complex sugars. Because those complex sugars that occur naturally in the body don't break down they need to find a place to go and so they end up being stored in the bones, tissues, organs, and muscles and it leads to many progressive symptoms: heart and airway disease, progressive stiffening of the joints, corneal clouding, spinal cord compression."
McFadyen has said that while the treatment is not a cure, it will keep the children alive while efforts to find a cure are made.
Violet's case had prompted many supporters to flood Premier Brad Wall's Twitter account with pleas for the funding, and Wall asked the ministry to look into the matter.
On Wednesday the approval came through.