Screening leads to earlier treatment, better results for SMA children: Study
Also, youngsters on more than 1 therapy achieve greater motor milestones
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- Newborn screening for SMA leads to earlier diagnosis and treatment, a new study found.
- Such early treatment was shown to significantly improve motor milestone achievement among SMA children.
- Receiving more than one treatment also was shown to lead to greater motor milestones.
Children with spinal muscular atrophy (SMA) who have two or fewer copies of the SMN2 gene — a feature typically associated with more severe disease — are more likely to start treatment early and reach key motor milestones if they are diagnosed through screening programs, a U.S. survey study suggests.
The results also indicate that children receiving more than one SMA therapy are more likely to achieve greater motor milestones than those given a single treatment. The researchers stressed, however, that more studies are needed to better understand the safety and benefits of this approach.
“The findings support the importance of newborn screening as part of an effective strategy for optimizing motor development, and the observed rise in polytherapy [using multiple therapies simultaneously] use highlights the need for further prospective evaluation of polytherapy’s long-term impact,” the researchers wrote.
The study, “Impact of Early Intervention on Motor Milestone Achievement in Spinal Muscular Atrophy: Insights from Cure SMA Survey Data,” was published in the journal Neurology and Therapy.
SMA is mostly caused by mutations in the SMN1 gene that contains instructions for making SMN, a protein that is essential for the function and survival of motor neurons — the nerve cells that control voluntary movement. As these cells are lost, individuals with SMA develop progressive muscle weakness that can affect movement, breathing, and other daily functions.
When SMN production is impaired, motor neurons become damaged and die, and this results in progressive muscle weakness that can affect movement, breathing, and other daily functions.
A second gene, SMN2, which also provides instructions for making the SMN protein, can partly compensate for SMN1 mutations. For this reason, children with fewer SMN2 copies tend to have more severe disease and a greater need for early treatment.
Cure SMA database used to look at screening programs
With the availability of disease-modifying therapies and the rollout of prenatal and newborn screening programs, many children are now diagnosed and treated much earlier than in the past. Still, the researchers noted that real-world data on how early diagnosis and treatment affect outcomes in children with up to two SMN2 gene copies remain limited.
To explore this, researchers at Cure SMA, a patient advocacy organization, and the University of Utah analyzed data from the nonprofit’s Community Update Survey, which includes caregiver-reported data from children with SMA collected between 2020 and 2024.
The analysis involved 414 survey responses covering 228 children with SMA who had two or fewer SMN2 copies. The children had a median age of 21 months, or about 1.8 years, and most (96%) had SMA type 1.
About 40% were diagnosed through screening programs — either prenatally, meaning during pregnancy, or via newborn screening — while the rest were diagnosed after symptoms appeared.
At the time of the first survey, 29% of children had achieved head control, and about one-third could roll, crawl, or sit without support. The data showed that 22% could stand with support, while 11% were able to walk independently.
Most newborns with SMA now diagnosed in first 3 weeks of life
ver time, earlier diagnosis became more common, the survey found.
Before 2018, most children (86%) were diagnosed after 4 months of age, while after 2021, 74% were diagnosed within the first 3 weeks of life. This shift was accompanied by earlier treatment, with the median age at treatment start dropping from 4.4 months to 19 days.
Importantly, starting treatment earlier was strongly associated with achieving greater motor milestones, the researchers noted. For example, children who began treatment before 3 weeks of age were 13.4 times more likely to reach higher-level motor milestones than those who started treatment after 4 months of age.
Significant differences were also seen for children who started treatment between 3 weeks and 2 months, or between 2 and 4 months, compared with those who began treatment after 4 months, though the magnitude became smaller with greater delays in treatment initiation.
The researchers also found children diagnosed through screening programs were treated earlier, at a median age of 20 days, while those diagnosed after symptoms emerged started treatment at a median age of 3.7 months. This translated in an 8.1 times greater likelihood of achieving higher milestones in those diagnosed through screening.
Children from higher-income households were more likely to achieve greater motor milestones, the researchers also observed. However, diagnosis through screening appeared to help reduce these differences by enabling earlier treatment regardless of income, the data showed.
This study highlights the pivotal role of screening in facilitating early treatment, a key predictor of higher-level motor milestone attainment for individuals with [2 or fewer] SMN2 copies.
In terms of treatment patterns, the use of single treatments decreased over time, from 74% in 2022 to 49% in 2024, Meanwhile, the use of combination approaches, or polytherapy, increased in the same period from 27% to 51%.
Further analyses showed that children receiving polytherapy were 2.4 times more likely to achieve greater motor milestones than those on a single therapy.
This was particularly evident among those diagnosed after symptoms began, according to the team. No clear difference were seen among children diagnosed through screening programs.
“This study highlights the pivotal role of screening in facilitating early treatment, a key predictor of higher-level motor milestone attainment for individuals with [2 or fewer] SMN2 copies,” the researchers wrote. The team added that “SMA diagnosis through newborn screening facilitates earlier treatment initiation, mitigates socioeconomic disparities, and supports advanced motor milestone achievement for children with [two or more] SMN2 copies.”
