Definitions of Spinal Muscular Atrophy Types
What is SMA 1, 2, 3, and 4. And Type 0!
In the last blog post we made a huge proclamation, that Emmett has progressed to presenting as a toddler with Spinal Muscular Atrophy Type 2 versus Type 1. However, I did not go into details nor did I provide any definitions. My friend, Sharon, commented that I made her do some research to figure out what was the difference, so here is a recap. *Please note that the descriptions of Emmett that follow are going back in time.
Layperson definition of the Types of Spinal Muscular Atrophy - PRIOR to SPINRAZA:
Spinal Muscular Atrophy describes the group of diseases in which a progressive degeneration of the spinal nerves causes a wasting of the muscles they control. 1 in 50 people are carriers of the survival motor neuron 1 gene, which decreases survival motor neuron protein, and this decrease causes the destruction of the nerves in the spinal cord that control neuromuscular growth and function. Carriers experience no symptons. Carriers do not develop the disease. When two carriers have a child, there is a 1 in 4 chance their child will have SMA. It can vary in severity.
SMA type 1 - most severe and the life expectancy is incredibly short. There are some amazing exceptions. Infants identified immediately upon birth may be referred to as SMA type 0.
SMA type 2 - children have greater SMN protein but still have a shortened lifespan and can never stand independently.
SMA type 3 - children have a normal lifespan but have life-long physical disabilities.
SMA type 4 - adult onset.
Prior to the drug Sprinraza there was No Treatment. Parents were told to love their little ones, provide them with as many experiences of life as they could, but realize that respite care was the only available care. Emmett was born in 2015 and he was involved in a worldwide trial of the drug that involved 124 little ones around the world. 2/3 of the little ones got the drug/1/3 of them got the placebo. The kids and families on the placebo were promised the drug after the test if the drug proved successful. The drug was amazing - the kids receiving the drug were improving. The kids on the placebo were literally dying. The company ended the test early, pushed for early approval of the drug from the USA FDA, Health Canada, etc.
At about three months of age Emmett lost the ability to move his legs. He never developed the ability to hold up his own head. His grip was weak and his wrists curled. He was a stomach breather. He was an incredibly floppy baby. And he was incredibly cute!
On August 18, 2015 Emmett was diagnosed with Spinal Muscular Atrophy, Type 1. By late September his alert eyes were rapidly looking about but his side to side head movement was virtually non-existent. He was losing the ability to control his muscles very quickly - with both arms failing to respond by the end of September 2015. Literally one day he could reach out and grab the ribbon from his helium balloon and then the next day he could not. It was heart breaking and I swear that even at his young age, Emmett knew that something was wrong with him. In October - I believe it was October 7, 2015 - Emmett got his first injection. At that time the drug was known as SMNrx. The drug was later called Nusinersin and, when it came to market, was called Spinraza. He was in the blind trial so we did not officially know if he was receiving the drub or a placebo until almost two years later - unofficially we started seeing improvements rather rapidly. (Interesting fact: the company that developed the drug was called ISIS. They changed their company name to IONIS. The drug was later purchased by BIOGEN.
Here's a blog post when Emmett turned one. The italics are a section copied from that post or you can click the link to read the entire post.
Take a look at Emmett when he was 12 months old.
"Spinal Muscular Atrophy, Type One is a challenging and terrifying disease. This SMA can strike at any age IF you have the right (I should probably say wrong) genetics. Both parents have to be carriers, and if they are then there is a 1:4 chance that their children will have SMA and a 2:4 chance that they will be SMA carriers but won't actually have the disease themselves. Scarey odds! If the disease presents itself before the child is six months old, then it is identified as Type 1. Emmett displayed symptoms before his diagnosis at five months but we didn't know what they were. Neither did the professionals during his check ups. It wasn't their fault. The highly trained nurses in the baby clinics and the family practice GP's saw a little boy who was demonstrated delayed development. SMA Type 1 would fall into a category of rare diseases that many medical practitioners may never see in their careers. Parents see their little one 24/7 and must be vigilant and push. And we've said before, when their GP did observe what concerned Alisha and Josh, Emmett was in to a paediatrician in less than 24 hours.
The one question that we have heard most often is "What is SMA, Type 1?". SMA being Spinal Muscular Atrophy. Here is another of my attempts to try to describe it. With almost no scientific phrases.
Picture your local multi-lane freeway. Traffic flowing perfectly both ways. Everything running like clockwork. No accidents. No flat tires. No construction (yes, that is a miracle in itself). Then see that some challenges intrude. Way ahead someone did get a flat tire or they ran out of gas resulting in a slight slow down of traffic. As you get closer to that incident, someone crashes into the rear end of another in the middle lanes. As you can imagine, traffic is slowed right down and comes to a virtual stop. That's irritating, but you know that in an hour or two you'll be back on your way. Maybe there's a bridge that is the only way across the country and it breaks, falling up, so that this main thoroughfare is out of commission or down to one lane for an unknown timeline. Or picture that there was a massive earthquake that has taken out literally kilometres of this highway. Obviously, the entire country is in chaos as a result of this natural disaster. Your car cannot ever traverse this expanse as the massive highway has literally disappeared. Since the government has no money to fix it (doesn't matter which country, as they're probably all broke), the only way to get from A to B now is to hike on foot or to take a donkey. But it is very hard to find a donkey, so you're left on foot. Of the hundreds of people who try to walk the distance, only a few can get through because it's tough. Climbing cliffs. Jumping crevasses (yes, there's ice everywhere). Crossing expanses of rushing water that has carried a few of the hikers off to the unknown. Very few of the hikers make it to their destination. Most just stop. The economy in this devastated area shuts down - completely. Until the engineers and construction crews can open up a new route nothing moves - and everyone hopes and prays for that a new route is opened.
This is similar to SMA, Type 1. The spinal column is the highway and it suffers a major blow. It is no longer healthy and the messages simply cannot get through. As a result the muscles begin to shut down.
The light at the end of this tunnel (maybe my analogy should have been a train tunnel that runs through a mountain) is the pharmaceutical trial that Emmett was allowed to participate in, beginning last fall. This is the scientists developing a drug that revitalizes the spinal column so that messages from the brain can get through. If this was our highway that had been devastated by the earthquake, the first step would be to open up some kind of walking path. Maybe with ropes across the crevasses and rushing rivers - if you can go hand over hand on the rope you can make it. Tough and very slow, but possible for some. Then the crew sets up a swinging rope bridge which enables many more to cross. With time, sturdier and more expansive paths are created. This experimental drug in this trial is like this.