What is Spinal Muscular Atrophy?

Because I've been suspecting SMA for a while, I had done quite a bit of reading about it to learn as much as I could. However, I didn't fully understand this disease until we met with the doctors at Nationwide.

I know a lot of our friends and family are wondering what exactly it is and how it progresses so I thought I'd dedicate a post to explaining as much as I can about it.

Spinal Muscular Atrophy is the number one genetic cause of death for infants. Children can only get SMA if both parents are carriers. This means that both parents have a healthy copy and a faulty copy of the SMN1 gene. Children who have SMA have inherited each parent's bad copy of the gene.

The SMN1 gene is responsible for producing the spinal motor neuron protein. That is basically what keeps our nerves healthy enough to tell our muscles what to do. Without that protein, our nerves begin to get sick and ultimately die. Which in turn leads to the atrophy of muscles. SMA affects an individual's ability to breathe and swallow, which ultimately leads to their death. It does not, however, affect their ability to think or learn.

There is however, a backup gene called SMN2. It is similar to SMN1 in that it also produces spinal motor neuron protein. But only about 10% of the protein that it produces is fully functional. So if an individual is born with zero copies of SMN1 and only one copy of SMN2, they can become very sick very quickly. The more copies of SMN2 a person has, the less severe their symptoms may be.

We know Cooper has zero copies of SMN1 but we're still waiting to hear how many copies of SMN2 he has.

It is estimated that 1 in 50 people are carriers of SMA. 1 in 11,000 babies are born with it.

If two parents are carriers there is a 25% chance they will have a child born with SMA. There is a 25% chance they will have a child who does not have SMA and is not a carrier. And there is a 50% chance they will have a child who does not have SMA but is a carrier.

There are 4 main types of SMA. Each with varying levels of severity.

SMA Type 1: Symptoms begin before 6 months and children usually will not have met the sitting milestone. This is the most severe of the two types. Without treatment, most infants will die before their second birthday.

SMA Type 2: Symptoms begin between 6 and 12 months. Children will usually be able to sit but will not walk. This is the type of SMA we believe Cooper has.

SMA Type 3: Symptoms begin after 12 months, usually even later in childhood. Children with type 3 will be able to walk.

SMA Type 4: Many living with SMA type 4 will have no symptoms or may not begin to see symptoms until after the age of 30. This is the least severe type of SMA.

Because this is genetic, we were concerned there was a chance Maisey may begin to experience symptoms as she gets older. We were told that because they would be receiving the same bad copies of the genes, typically siblings would have the same type. Which means Maisey shouldn't have to worry about ever experiencing symptoms of SMA, although she may be a carrier.

Because of huge advancements in research, there are now two amazing treatments for this awful disease. Both are most effective when given before children become symptomatic. One is a gene therapy called Zolgensma. It's a one time IV injection that replaces the missing SMN1 gene. Children who receive this treatment have to receive it before two years of age. The other treatment is called Spinraza. It is administered through a lumbar puncture and must be given every four months. Spinraza works by targeting the SMN2 gene and causing it to make more complete protein.

Some facts:

It is estimated that there are 12,053 individuals in the US living with SMA.

The estimated number of babies born annually with SMA is 344.

There are an estimated 6,543,349 carriers of SMA in the United States.

Having a child diagnosed with this disease has been overwhelming to say the least. I spent the first day and a half after his diagnosis crying on and off and fearing the absolute worst. I was afraid to have hope that things could get better because I was afraid of being let down when we went to Nationwide. I was terrified they would tell us he couldn't be saved. Instead they told us our treatment options and told us to have hope. They told us they fully expect to see improvement with both treatment options. And they also told us to always, always have hope that some day there will be a cure.