Newborn screening tied to better daily function in children with SMA
Early diagnosis, treatment linked to more independence at school age
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- SMA newborn screening and early treatment were linked to better long-term function.
- Home, school, and multidisciplinary support may help children build independence.
- Children diagnosed through newborn screening were 33 times as likely to meet expected scores across all domains.
Children with spinal muscular atrophy (SMA) who were diagnosed through newborn screening and treated early had better long-term independence and daily functioning, especially when supported by multidisciplinary care at home and at school, according to a real-world study from Australia.
“Multidisciplinary care is important to meet the changing and individualised needs of children with SMA, especially as they transition to complete higher motor tasks and complex everyday activities,” the researchers wrote. “Health professionals and families must focus on skills and targeted interventions for promoting independence.”
Newborn screening linked to better long-term function
The study, “Adaptive functioning in school-aged children with spinal muscular atrophy in the treatment era: a non-randomised cohort study,” was published in The Lancet Regional Health – Western Pacific. It is based on data from school-aged children followed for a median of more than five years, capturing some of the first longer-term real-world outcomes in children diagnosed through newborn screening.
SMA is most often caused by mutations in both copies of the SMN1 gene. These genetic mutations lead motor neurons — the nerve cells that control movement — to gradually die, causing muscle weakness and poor muscle tone. Disease-modifying treatments can slow the progression of symptoms, and starting them as early as possible is key to achieving the best outcomes.
However, “long-term outcomes focused on functional independence for children have not been explored,” the researchers wrote. To study this, they followed 39 children, ages 4 to 12 years, who had been treated for SMA for a median of about 5.6 years. Eighteen were diagnosed through newborn screening, most before symptoms were clinically apparent. The other 21 children were diagnosed through clinical referral, generally after symptoms started.
To understand how well children function in everyday life, the researchers used the Pediatric Evaluation of Disability Inventory Computer Adaptive Test (PEDI-CAT). This questionnaire, completed by caregivers, compares how independently a child performs daily activities, moves around, interacts socially, and manages multistep tasks with what is expected for their age.
Sixteen children scored within the typically expected range for all four PEDI-CAT domains. Children diagnosed through newborn screening were more than 33 times as likely as those diagnosed through clinical referral to score within the typically expected range across all four domains. Nearly all children had age-appropriate social and cognitive functioning (97%) and could manage responsibilities such as their daily routine (90%).
A greater proportion of children diagnosed through newborn screening scored within the expected range for daily activities (94% vs. 57%) and mobility (78% vs. 10%) compared with those who had been referred clinically. They also were significantly less likely to use manual or powered wheelchairs to move around (28% vs. 76%).
SMN2 copy number also shaped long-term outcomes
The researchers also looked at the number of copies of the SMN2 gene each child had. This gene produces small amounts of SMN protein — the same protein encoded by the SMN1 gene — and more copies are generally linked to milder forms of SMA. Children with more copies tended to have milder symptoms. For example, all children diagnosed through newborn screening with three copies of the SMN2 gene scored within the expected range across all PEDI-CAT domains.
Children diagnosed through newborn screening also performed better on walking and motor function tests. Overall, many children achieved independence in everyday life, especially when supported by assistive technology and school accommodations. Fifteen children did not use assistive technologies or physical assistance to complete everyday tasks at home or school; 10 of them, or 67%, had been diagnosed through newborn screening.
Among caregivers who completed a stress survey, none reported elevated stress scores, and many described positive experiences in caring for their children. “They enjoyed spending time with their children, their children were an important source of affection and enjoyment, and they were happy in their role as a parent,” the researchers wrote. Caregivers also found tools such as the PEDI-CAT useful because they reflected children’s real-world abilities rather than only clinical measurements.
At the time of the study, children diagnosed through newborn screening were a median of 3.8 years younger than those diagnosed through clinical referral, and more of them were expected to develop severe disease early on. Even so, they showed better long-term outcomes than the older children diagnosed later. “The study findings are magnified in this context,” the researchers wrote.
