A new drug is offering hope for the family of a little girl whose genetic defect causes mobility issues similar to that of polio and amyotrophic lateral sclerosis (ALS).

Four-year-old Lexi Pacini, of Colorado Springs, was diagnosed with type 2 spinal muscular atrophy (SMA) as a toddler. The rare disease is marked by the absence of a gene that codes protein signals from motor neurons to muscles, and it leads muscles to weaken to the point of atrophy.

“Around 11 months, she still wasn’t crawling,” her mother, Tammy Pacini, told Children’s Hospital Colorado, where Lexi is being treated, in a news release. “Our pediatrician referred us to a physical therapist, who just chalked it up to laziness. But as time went on, we knew something was wrong.”

At the time, doctors gave Lexi a prognosis of eventual immobility and an inability to breathe.

But the drug nusinersen, which is being tested in a double-blinded study and which Lexi is receiving via an open label, is helping Lexi walk again. Nusinersen upregulates another protein, SMN2, which Lexi did inherit from her parents.

“One of the qualifications for this trial was that the kids could sit up but not walk,” Dr. Julie Parsons, a pediatric neurologist at the hospital, said in a news release. “Lexi’s taking steps now, which is pretty darn cool.”

More on this...

During preliminary studies, nusinersen showed promise for children like Lexi, and the Food and Drug Administration (FDA) approved the drug late last year as a treatment for spinal muscular atrophy.

“The hope is that, with treatment, these children will stabilize,” Parsons said in the release, “or that they will actually get stronger.”

With renewed hope for Lexi’s mobility, Tammy enrolled her daughter in dance classes.

“She dances the way she knows how, in her walker,” Tammy told Children’s Hospital Colorado in the release. “She just doesn’t give up. She wonders why she can’t do certain things, and we’ll tell her, ‘Well, you’re just not as strong. You don’t have as much muscle.’ And she’ll just say, ‘No, I have muscles. I’m strong.’”