1OfTheGoodGuys

wrist flexor muscles are stronger than extensors. when you lose strength in both from SMA, your flexors overwhelm the extensors and your natural resting position is more of a flexed "boxing fist" position.

Try it out: you can squeeze your hands into a fist really hard, but it's much harder to open your hand against resistance.

Perhaps you guys can help explain to me the differentiation in SMA types. Historically, they were based on developmental milestones (unable to sit up=1 with death around 2, unable to stand=2, teenage onset=3, adult onset=4), but you seem to be referencing SMN2 copy number variation, which obviously is related. Is there a more definitive approach now for diagnosing type?

There is a ton of research. Check out OMIM for a review of some of it.

Since the problem isn't with the muscles, but the nerves, there is essentially nothing you could do in the long run. If you got huge before, you'd likely retain it for slightly longer, but without the nerves driving, you get atrophy. Check out the SMA muscle histology to see what happens to the muscle fibers.

SMA (in my niece) inspired me to become a doctor, and I thought I'd share that a promising treatment, gene therapy, is now in clinical trials!

Gene Transfer Clinical Trial for Spinal Muscular Atrophy Type 1

They are recruiting patients now, if you know of someone with SMA 1 6mo-1yr, they could receive life saving treatment now!