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Key Differences Between Spinraza and ZOLGENSMA
Over the past couple of weeks, I have received numerous questions regarding the differences between Spinraza and ZOLGENSMA. On Friday, May 24, 2019, ZOLGENSMA became the second FDA-approved treatment for Spinal Muscular Atrophy (SMA). With this approval comes a lot of questions regarding these two treatments. Please understand that I’m not a doctor, but I’m going to try to describe the differences between Spinraza and ZOLGENSMA in layman’s terms.
The human body is composed of a myriad cells and genes that make us who we are. SMA is caused by a mutation in the SMN1 gene, and this mutation is the reason why we have this terrible disease. Everyone has a copy of the SMN1 gene, and it’s known as the SMN2 gene. This SMN2 gene produces the same type of protein that the SMN1 gene produces, only at lower amounts.
Spinraza works by trying to repair the SMN2 gene. SMN is an acronym that stands for Survival Motor Neuron. Without getting too technical, think of it this way. If you take a sentence that is 10 words long, and remove the 7th word, this sentence would not make sense. This missing 7th word is known as the 7th exon. When this 7th exon is removed, it produces a faulty message, which in turn, makes this an insufficient or defective protein.
Spinraza, also known as Nusinersen, fixes this SMN2 splicing error. Researchers and scientists have developed Spinraza to bind this missing or removed exon 7 sequence back in the genetic string, essentially putting this missing 7th word back in the sentence. Binding is just a process where this 7th exon will not be removed. After binding the exon 7 back in this genetic sequence, SMN2 becomes functional, giving those of us with SMA the protein that we need so that we can sustain the muscle that we already have, and possibly get stronger. While I know that my explanation may have been somewhat crude, I found an excellent video that fully explains this process.
https://www.youtube.com/watch?v=YLluIVwg_y4&index=4&list=LLu6wTX2VsrOIgRP7xXcsAFA&t=0s
ZOLGENSMA, while being the second FDA approved treatment for SMA, is the first gene therapy of its kind. Instead of working on the SMN2 gene, like Spinraza, ZOLGENSMA replaces the missing or defective SMN1 gene. Even though Spinraza repairs the SMN2 gene, the SMN2 gene still produces less functional protein than the SMN1 gene. Since ZOLGENSMA replaces the missing or defective SMN1 gene, this provides patients with a fully functioning SMN protein.
One thing that all of us need to remember is that Spinraza and ZOLGENSMA are the first of their kind. Four years ago, those of us with SMA had no means of stopping the progression of the disease. Now, we have two viable treatments, and many more groundbreaking medical advancements on the way.
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