Consultation on a proposal to fund a new treatment for spinal muscular atrophy (SMA) is now underway.
Risdiplam, taken orally once a day, can significantly improve the lives of young people with the disease and is well-tolerated over years of treatment, a long-running study has shown.
Drug-buying agency Pharmac says it has already received clinical advice to fund it from internal committees, which said it "will make a significant difference to the lives of people with SMA".
Pharmac director of operations Lisa Williams told Morning Report on Thursday between 30 and 50 Kiwis would be eligible under the proposed criteria.
Risdiplam is manufactured by multinational pharmaceutical company Roche, which sells it under the brand name Evrysdi. It was first approved for use in treating SMA in the US in 2020.
SMA is caused by a mutation in a gene, SMN1, involved in the production of a protein called SMN. Risdiplam works by modifying another gene, SMN2, to produce more of the protein as a 'back-up'.
It's believed one person in between 40 and 60 carries the mutation. If two carriers have a child, there is a one-in-four chance their child will have it.
Around one in 10,000 children is born with SMA, which - without treatment - progressively gets worse and is often fatal, particularly in infants and younger children.
Last year, RNZ spoke to a Tauranga couple who split their family apart so their daughter had a chance to access funded treatment for another SMA treatment, nusinersen, in Australia.
Pharmac in December announced it would fund nusinersen, manufactured by US multinational Biogen and sold under the brand name Spinraza.
Williams said if the proposal for risdiplam was approved, patients here would have a choice between the two drugs. Some people in New Zealand are already taking risdiplam under compassionate access, Pharmac's website said.
"We are asking people for feedback on the proposed criteria that we're going to have in place and other aspects about the practical implementation of funding for this treatment."
The cost of funding risdiplam is confidential. Both nusinersen and risdiplam are considered 'orphan drugs' by international agencies - meaning the conditions these treat are too rare for the drug to be manufactured at a profit, so are reliant on governmental funding.
"It's a worthwhile investment," Williams said.
Details of the proposal and instructions on how to provide feedback are on Pharmac's website.