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Newborn Screening for Spinal Muscular Atrophy: A 2.5-Year Experience in Hyogo Prefecture, Japan
Shoko Sonehara1, Ryosuke Bo1, Yoshinori Nambu1
1Department of Pediatrics, Kobe University Graduate School of Medicine, 7-5-1, Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan.
Insights
Newborn screening for spinal muscular atrophy (SMA) in Japan identified three infants, enabling early treatment and improved motor and respiratory outcomes. Nationwide SMA screening should be considered for better infant health.
Area of Science:
- Genetics and Genetic Diseases
- Pediatric Neurology
- Public Health and Screening Programs
Background:
- Early diagnosis and treatment of spinal muscular atrophy (SMA) are crucial for favorable outcomes.
- Disease-modifying drugs can significantly improve motor and respiratory function in infants with SMA.
- Newborn screening (NBS) for SMA has been initiated in Japan, but clinical results require further reporting.
Purpose of the Study:
- To report the initial clinical findings of a pilot newborn screening program for spinal muscular atrophy (SMA) in Hyogo Prefecture, Japan.
- To evaluate the effectiveness of early detection and treatment of SMA through NBS.
- To assess the motor and respiratory outcomes in infants diagnosed with SMA via NBS.
Main Methods:
- A pilot SMA-NBS program screened approximately 16,000 infants over 2.5 years (February 2021 onwards).
- Retrospective collection of clinical data from 17 infants who tested positive.
- Genetic testing (SMN2 copy number, SMN1/2 hybrid gene) and follow-up assessments were conducted.
Main Results:
- Out of 17 infants who tested positive, 14 were false positives, and three were diagnosed with SMA.
- The three diagnosed infants included varying SMN2 copy numbers and one with a hybrid gene; two were asymptomatic at diagnosis.
- Early treatment (within 1-8 months) led to improved motor function scores and no requirement for respiratory support in all three SMA patients.
Conclusions:
- Newborn screening for SMA enables early identification and timely treatment, significantly improving motor and respiratory outcomes.
- The pilot study demonstrates the clinical utility and positive impact of SMA NBS in improving infant health.
- Nationwide implementation of SMA NBS is recommended to ensure early intervention for all affected infants.
Abstract:
Newborn screening (NBS) for spinal muscular atrophy (SMA) is necessary, as favorable outcomes can be achieved by treatment with disease-modifying drugs in early infancy. Although SMA-NBS has been initiated in Japan, its clinical results have not been fully reported. We report the findings of the initial 2.5 years of a pilot SMA-NBS of approximately 16,000 infants conducted from February 2021 in Hyogo Prefecture, Japan. Clinical data of 17 infants who tested positive were retrospectively obtained from the NBS follow-up centers participating in this multicenter cohort observational study. Genetic testing revealed 14 false positives, and three infants were diagnosed with SMA. Case 1 had two copies of survival motor neuron (SMN) 2 and showed SMA-related symptoms at diagnosis. Case 2 was asymptomatic, with two copies of SMN2. Asymptomatic case 3 had four copies of SMN2 exon 7, including the SMN1/2 hybrid gene. Cases 1 and 2 were treated within 1 month and case 3 at 8 months. All the patients showed improved motor function scores and did not require respiratory support. The identification of infants with SMA via NBS and early treatment improved their motor and respiratory outcomes. Thus, implementation of SMA-NBS at a nationwide scale should be considered.
