SMA is an inborn error of metabolism, clearly rare because there are 1 million 0-14 y.o children in Ireland with about 65,000 more coming on stream every year but only 25 of them have SMA. The error occurs as a mutation in the SMN [survival motor neuron] gene located on chromosome 5. The SMN protein is one member of a complex of proteins that process mRNAs before export from the nucleus. Several different defective mutations have been logged among sick children who present with progressive loss of muscle tone. Each lesion will give a different prognosis; several are associated with SMA1, the worst condition with such early onset that the poor wean never gets the ooof to sit up. Other changes will result in later onset of the clinical symptoms: SMA2 (Grace's cohort) get to sit but not to stand; while SMA3, the mildest form, learn to stand and have the expectation of getting to vote. Each case is spontaneous - it doesn't run in families because with SMA it's hard enough to breathe and feed yourself, let alone make babies.
The peculiarity of SMN is that most of us have two copies. A 300,000 bp chunk of Chr5, has been duplicated and reinserted backwards further along the chromosome. This duplicated region includes SMN2 which is identical to SMN1 but usually kept on the back-burner. Spinraza / Nusinersen works on this information by encouraging SMN2 to perk up and make full length copies of the protein that can compensate for the duff copies of SMN1. Spinraza is an anti-sense DNA which cannot be administered intravenously, let alone orally, but must be injected directly into the cerebro-spinal fluid. As it has a finite half-life, this life-enhancing fluid must be given 4 times a year. That's less frequently than Factor VIII for haemophilia, but the market price for Spinraza is an eye-watering $125,000 a pop or €500,000/year for starters, trailing off in subsequent years as the number of booster injections is reduced.
The maths is beguilingly symmetrical.
- Team Haemophilia has more [N=200] members who need their therapy, more often, but the cost per dose is about €2,000. Cost to the tax-payer is €60 million annually.
- SMA United musters about 25 people, and the NCPE reckons the cost will be a rolling €10-20 million.
source] - I met him at mature student interviews a couple of weeks ago! - life itself depends on the intervention. We the tax-payer just cannot do everything for everyone without we embrace a highly productive socialist paradise with to each according to his need. Why not be a utilitarian?
The drug market is regulated at two levels:
- EMA [European Medicines Agency; = FDA in USA] decides if a new drug is a) safe and b) works to specification: a pass here allows the drug to be sold
- NCPE decides if the drug is so good that the government will pick up the tab.
"The impulse to serve the collective many over the individual few is hard to assail." is an aposite quote from a NYT longform on hospice care for children. When the amazing and ingenious therapies run out, a place needs to be set aside, preferably without drips and tubes and perpetually beeping monitors, where the poor child can go in peace.