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Newborn screening for spinal muscular atrophy in Germany: clinical results after 2 years
Katharina Vill1, Oliver Schwartz2, Astrid Blaschek1
1Dr. v. Hauner Children's Hospital, Department of Pediatric Neurology and Developmental Medicine, LMU - University of Munich, Lindwurmstraße 4, 80337, München, Germany.
Insights
Newborn screening for spinal muscular atrophy (SMA) enables early diagnosis and treatment, significantly improving outcomes for affected infants. Prompt intervention prevents severe disability and enhances neurodevelopmental progress in children with SMA.
Area of Science:
- Genetics
- Neurology
- Pediatrics
Background:
- Spinal muscular atrophy (SMA) is a leading cause of neurodegenerative disease in children.
- Early diagnosis and intervention are critical due to the irreversible nature of motor neuron damage.
- Assessing the impact of genetic newborn screening for SMA on patient outcomes is essential.
Purpose of the Study:
- To evaluate the effectiveness of genetic newborn screening for SMA.
- To determine the impact of early diagnosis and treatment on neurodevelopmental outcomes in SMA patients.
- To support the implementation of SMA newborn screening programs.
Main Methods:
- Clinical data from 43 SMA patients identified via SMN1 gene analysis from dried blood spots were collected.
- Patients were screened between January 2018 and January 2020 in Germany.
- Follow-up included neurophysiological examinations and standardized physiotherapeutic assessments.
Main Results:
- Newborn screening detected SMA with an incidence of 1:6910 in Germany.
- Pre-symptomatic treatment initiated between 14-39 days of life resulted in asymptomatic patients.
- Untreated SMA patients with 2 SMN2 copies died, while those with 3 copies developed weakness; early treatment prevented respiratory symptoms in patients with 2 copies.
Conclusions:
- Early identification and prompt treatment of SMA through newborn screening significantly improve neurodevelopmental outcomes.
- Electrophysiology can support the urgency for timely SMA therapy.
- A short interval between screening and referral to specialized treatment centers is crucial.
Background:
Spinal muscular atrophy (SMA) is the most common neurodegenerative disease in childhood. Since motor neuron injury is usually not reversible, early diagnosis and treatment are essential to prevent major disability. Our objective was to assess the impact of genetic newborn screening for SMA on outcome.
Methods:
We provided clinical data from 43 SMA patients, identified via polymerase chain reaction of the SMN1 gene from dried blood spots between January 2018 and January 2020 in Germany. Follow-up included neurophysiological examinations and standardized physiotherapeutic testing.
Results:
Detection of SMA with newborn screening was consistent with known incidence in Germany. Birth prevalence was 1:6910; 39.5% had 2 SMN2 copies, 23% had 3 SMN2 copies, 32.5% had 4 copies, and 4.5% had 5 copies of the SMN2 gene. Treatment with SMA-specific medication could be started at the age of 14-39 days in 21 patients. Pre-symptomatically treated patients remained throughout asymptomatic within the observation period. 47% of patients with 2 SMN2 copies showed early, presumably intrauterine onset of disease. These patients reached motor milestones with delay; none of them developed respiratory symptoms. Untreated children with 2 SMN2 copies died. Untreated children with 3 SMN2 copies developed proximal weakness in their first year. In patients with ≥ 4 SMN2 copies, a follow-up strategy of "watchful waiting" was applied despite the fact that one of them was treated from the age of 6 months. Two infant siblings with 4 SMN2 copies were identified with a missed diagnosis of SMA type 3.
Conclusion:
Identification of newborns with infantile SMA and prompt SMA-specific treatment substantially improves neurodevelopmental outcome, and we recommend implementation in the public newborn screening in countries where therapy is available. Electrophysiology is a relevant parameter to support the urgency of therapy. There has to be a short time interval between a positive screening result and referral to a therapy-ready specialized treatment center.
