…and also the most expensive to treat.
My name is Antonio and I suffer from spinal muscular atrophy (SMA, for friends).
My life expectancy was only a few years when I was born, almost half a century ago. And all because I “got” a rare, neurodegenerative disease, which is among the genetic diseases with the highest associated mortality.
What happens, simply put, is that my motor neurons (the “cables” that link the spinal cord to the muscles) gradually degenerate and end up dying. This has kept me in a wheelchair for most of my life. And over time, the involvement of the respiratory muscles can lead to the fatal outcome.
But since I am also a scientist, I must add that I have discovered that SMA is the most beautiful disease in the world… at a molecular level.
How does spinal muscular atrophy occur?
SMA is a genetic disease caused by the mutation or loss of a gene called SMN1. If our mother and father have a mutated copy (one of two copies each), and we are unlucky enough to inherit these two defective copies, we are likely to get SMA.
This gene contains the information to guide the construction of a protein called SMN. Its name comes from the suggestive acronym survival of motor neuron, and it plays very important roles in our body. In fact, without SMNs, there is no survival of motor neurons, and no possibility of life itself. This is because these cells are essential for carrying out muscle movements, including those of the diaphragm or pharynx, which allow us to breathe and eat.
So how do SMA patients survive? Because it turns out that there is a second gene in the human genome, called SMN2, which also allows us to build the same SMN protein.
In general, those who lack the SMN1 gene and have only one copy of SMN2 have a severe case of the disease, with more rapid progression (type I). Those with two copies have a milder case (type II). Finally, with three or more copies we have an even milder case (type III) and the chances of living longer are increased.
Given this reality, we can conclude that evolution “invented” the copy of SMN1 in humans to have a lifesaver in the case of losing the main gene. Beautiful, isn’t it?
Extortionately expensive treatments
Available treatments are among the most expensive in the world. Zolgensma costs no less than…. two million euros per dose! That makes it the most expensive disease in the world. Fortunately, only one dose is needed. In the case of Nusinersen and Risdiplam, it would cost between 400,000 and 800,000 euros per year (and, of course, per patient).
Why these sky-high prices? We will never know. Pharmaceutical companies usually negotiate the price of the drug independently in each country and with zero transparency. This leads them to consider the drug as a commodity, the price of which is not necessarily linked to its development and production cost. Rather, it is the price one is willing to pay for the life and well-being of patients in every part of the world.
By the way, none of the three drugs cures. They only slow down the progression of the disease—which is no small thing.
In conclusion, it is indisputable that SMA is a devastating disease, and that SMA patients will always have the right to complain about the bad luck we were born with. But at least I hope I have shown that this disease has a special charm at the molecular level which, for those of us who suffer from it, also gives us a certain right to call it “the most beautiful disease in the world”.
Antonio J. Pérez Pulido is a Doctor in Biology with a specialization in Bioinformatics and is also an SMA patient and co-leader of a project to search for genes modifying the SMN2 gene expression. Excerpted from The Conversation.
