(melancholic music) - [Narrator] Jase got his first dose of the experimental treatment called nusinersen through an infusion into his spinal fluid when he was just 18 days old.

- [Mom] We were on a journey.

It was kind of like miracle or bust.

We're gonna have a miracle or we're just going to lose him.

Our hope was that maybe our baby would be able to at least sit or eat normal food or maybe he would walk even.

What are you doing?

Are you sitting up?

It's a miracle.

It's January.

January 24th.

- [Dad] As time goes on, and Jase begins to do things that Ariel didn't.

- [Mom] Is crawling.

- There's this new hope.

Like hey, it looks like we're going to get to raise him.

- [Mom] I love how you walk with your hands up.

Yes.

- Yay.

- We were at some friend's house for the evening and I set Jase down on the floor.

Daddy's there.

And Jase just took a couple steps and it was like oh my goodness, he's doing it.

Like that's more than he's ever done before.

Oh, good job.

- Are you ready to go?

- [Mom] Jase was just going back and forth between us and we kept backing up and he would go further.

- Come to daddy.

You're doing so good.

Whoa!

That was amazing.

- [All] Yay.

- [Mom] Everyone that was there was standing around cheering and it was awesome.

- [Man] Yay, whoa.

- That's wonderful.

- And then on our way home, it was just quiet and we were all just kind of like (sighing).

Like did that really?

This really happened.

(trampoline squeaking) - [Narrator] Jase recently celebrated his third birthday unaware that he is a medical pioneer who represents the promise of a genomic revolution decades in the making.

- I'm gonna get you.

- [Narrator] He and two dozen other pre-symptomatic children in the trial are all doing well.

They need spinal infusions of the drug every few months but without them, they would almost certainly no longer be alive.

(Jase chuckling) - I bet you can't catch me.

(Jase screaming) - There's just time in this journey where the full seriousness of it hits us and we're like we're looking at something and we're holding a person who like Earth has never seen anything like this before.

This has not been possible.

This is amazing and yet it's also really normal.

- I'm a dreamer.

I mean, he's just my little son so I'm just taking these moments for what they are and loving him, loving life.

Loving the season of life that we're in.

After each moment where there has been a dramatic success doesn't just enliven the people who are working on that disease, it has ripples across the field.

It's one more reason to believe that those decades of really hard slogging are finally beginning to yield up some really remarkable events and that makes everybody interested in working harder and probably recruits new people into the field who maybe were holding back for fear that this wasn't ready yet.

It seems to be ready now.