Early Spinal Muscular Atrophy Treatment Tied to Milder Pediatric Phenotype

New data from Cure SMA's annual Community Update Survey showed that children with spinal muscular atrophy (SMA) who began disease-modifying treatment (DMT) within their first weeks of life walked independently more often and had fewer musculoskeletal and swallowing-related comorbidities than children treated later, as newborn screening and an expanding range of therapies continue to reshape the disease's clinical picture.¹

Researchers presented the findings at the 2026 American Association of Neuromuscular & Electrodiagnostic Medicine (AANEM) Annual Meeting and MGFA Scientific Session in Orlando, Florida.

“Since 2017, I've been doing an annual Community Update Survey that asks about demographics, health information, treatments, unmet needs, and quality-of-life metrics for everyone living with SMA,” lead author Lisa Belter, MPH, director of research analytics at Cure SMA, said in an interview with NeurologyLive.

“Earlier this year, we published data in Neurology and Therapy showing that age at first treatment was the biggest predictor of motor milestone gain in children with 2 or fewer SMN2 copies," she added. “Children treated under 21 days of age had 13.4-fold greater odds of reaching higher motor milestones than children treated later. So, we went back to our survey data to describe what these children look like.”

That earlier analysis, published in April 2026, compared children treated before 3 weeks of age with those treated after 4 months, drawing on 414 survey responses from 228 children with 2 or fewer SMN2 copies (90.8% with 2 copies) collected from 2020 through 2024.²

For the AANEM presentation, the investigators returned to the 2025 Community Update Survey and split a separate cohort by a different threshold, defining “early treated” as children who received their first DMT before 90 days of life and “later treated” as those treated after 90 days. The final sample included 41 early-treated and 32 later-treated children.¹

Mean age at the time of the survey was 4.1 years in the early-treated group and 6.0 years in the later-treated group. Nearly half of the early-treated children (48.8%) were diagnosed with SMA type 1, while nearly half of the later-treated children (47.1%) were diagnosed with type 2.

At the time of the survey, 73.2% of early-treated children were able to walk independently, compared with 36.7% of later-treated children. Scoliosis was present in 24.4% of the early-treated group versus 62.5% of the later-treated group, and 7.3% versus 19.4% reported trouble swallowing at least half the time.

Belter also described a broader, supplementary analysis presented alongside the formal abstract that used a different cutoff: children ages 2 to 9 from the 2025 and 2026 survey years, divided into those treated before versus after 21 days of age, rather than the abstract's 90-day threshold. “We took our Community Update Survey data from 2025 and 2026 and divided children between the ages of 2 and 9 into those treated under 21 days of age and those treated over 21 days of age,” she said.

“For the early-treated group, most caregivers reported their child has SMA type 1 with 2 SMN2 copies, and yet 83% of them could walk alone at the time of the survey,” Belter continued. “Historically, someone with SMA type 1 and 2 SMN2 copies would not be expected to sit unsupported, let alone walk.”

That 83% figure comes from this separate, 21-day-cutoff analysis and is not directly comparable to the abstract's own 73.2% figure, which used the 90-day cutoff and a different, smaller cohort limited to the 2025 survey year.

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“Scoliosis diagnosis, hip dysplasia, dysphagia, and neurocognitive deficits were also much lower in the earlier-treated cohort versus the later-treated cohort,” Belter said. “It's just really showing, using caregiver-reported data, the benefit of treating early versus treating late.”

Newborn screening for SMA, added to the federal Recommended Uniform Screening Panel in 2018, became available in all 50 states in January 2024, when Hawaii and Nevada completed rollout.³ Three DMTs are now approved in the United States: nusinersen (Spinraza), first approved in December 2016; onasemnogene abeparvovec (Zolgensma), a gene therapy approved in May 2019; and risdiplam (Evrysdi), approved in August 2020 for patients 2 months and older.^4-6

“I think it's important to really put a number on what 'early' means, because I hear from a lot of families and clinicians, 'It's great, I got this baby treated at 4 months, they got treated so early,' and it's like, we need to get earlier than that,” Belter said. “Our data suggests at most 3 weeks or earlier.”

“It's important for the neurologist to advocate for urgency, and for insurance processes to be as streamlined as possible, without having to jump through prior authorizations," she concluded. “Some hospitals are using bridging therapy to get treatment started earlier, and I think that should be more of a standard, more widely implemented, to get children treated as early as possible.”

Click here for more AANEM 2026 coverage.

REFERENCES
1. Belter L, Welsh E, Whitmire S, Curry M. Evaluating the evolving spinal muscular atrophy phenotype in children: results from the Cure SMA Community Update Survey. Presented at: 2026 AANEM Annual Meeting and MGFA Scientific Session; September 29-October 2, 2026; Orlando, FL.
2. Lawrence KAK, Belter L, Curry M, Tak C, Schroth M. Impact of early intervention on motor milestone achievement in spinal muscular atrophy: insights from Cure SMA survey data. Neurol Ther. 2026;15(4):1557-1572. doi:10.1007/s40120-026-00943-x
3. All 50 states now screening newborns for SMA. Published January 2024. Accessed October 2, 2026. https://www.curesma.org/wp-content/uploads/2024/01/All-50-States-Now-Screening-Newborns-for-SMA.pdf
4. Spinraza (nusinersen) FDA approval history. Accessed October 2, 2026. https://www.drugs.com/history/spinraza.html
5. Zolgensma (onasemnogene abeparvovec-xioi) FDA approval history. Accessed October 2, 2026. https://www.drugs.com/history/zolgensma.html
6. Evrysdi (risdiplam) FDA approval history. Accessed October 2, 2026. https://www.drugs.com/history/evrysdi.html