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  • Looking to Study

    Posted by KenBrace on August 11, 2023 at 10:04 am

    Hey everyone! Been doing some research into SMA and trying to deepen my understanding of what causes it and how the various treatments work to address that. My girlfriend has Type 2 so I’m hoping to gain some insight that can help us with our decision making.

    deann-r replied 10 months, 1 week ago 2 Members · 3 Replies
  • 3 Replies
  • deann-r

    Member
    August 12, 2023 at 10:22 am

    Nice to have you here. I’m a moderator along with Alyssa and Kevin. I hope you’ll find lots of great information. As far as what causes SMA, it’s kind of complicated to explain, but my basic explanation is that it’s a genetic glitch passed down from our parents.

    Here’s my understanding. To have SMA both parents are most likely carriers of a faulty gene. Everyone has two of these genes (I’m not 100% if gene is the right term but I think so) and if you have an unaffected one and a faulty one you’re a carrier. Since they’re just carriers and not affected they probably are unaware unless it’s shown up in family history. Each parent passes down one gene to their child. A child could receive an unaffected gene from each parent (25% chance), therefore not having SMA or being a carrier. They could receive one unaffected gene and one faulty gene (50% chance) making them a carrier but unaffected. Or they could receive both faulty genes and have SMA (also a 25% chance.) If you dig around you can probably find a great chart that explains it better than I just did.

    It’s a common misconception that if you have SMA your kids will have it. It’s true they’ll be carriers but unless the other parent is a carrier they wouldn’t have SMA because you get one gene from each parent.

    How do treatments come into play? Since those of us with SMA got the faulty genes we don’t have the SMN1 gene that produce neurons that create protein muscles need to function. Luckily there’s a backup gene, SMN2, that also creates functional protein, however like a lot of backup vehicles there’s a glitch. Most of the treatments are aimed at fixing that glitch to allow those neurons to create more functional protein. Oddly enough with SMA the number of copies of this SMN2 gene varies. Typically the severity of SMA is indirectly correlated with the number of SMN2 copies however there are other factors.

    Again this is all my interpretation. Hopefully I didn’t confuse you too much. Let me know if I can clarify anything or if you have more questions.

  • KenBrace

    Member
    August 13, 2023 at 7:47 pm

    Hi Dianne,

    Thank you that was a good summary. One aspect I’m really interested in are the SMN-plus possibilities. If the backup SMN gene is repaired then the primary issue is resolved but there may still be ways to help the body regrow and strengthen nerves. I can accept that some of the motor neurons may not be capable of coming back to life but I am interested in what ways there might be to heal neurons that are still living and also regrowing their connections into the muscle tissue. I will continue to research more and look forward to reading the forums.

    • deann-r

      Member
      August 14, 2023 at 8:52 pm

      I had the dead vs dormant discussion with my neurologist a while back. Unfortunately it’s just an unknown at this point. Also something to consider is that the backup gene doesn’t produce as much as the original missing gene would. I highly recommend checking out some of Michael Morale’s videos on the upcoming drug in trial apitegromab. Here’s a link to an older video, but I think he has an update coming out Sunday.

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