A recently published study in SSRN has revealed that undergoing newborn screening (NBS) can positively influence the resulting developmental outcomes of patients with spinal muscular atrophy (SMA).
Moreover, NBSs play a crucial role in enabling patients to receive gene therapy as soon as possible to improve their motor developmental outcome, the researchers found.
Read more about SMA therapies
Recently, SMA has become treatable as a result of the development of the antisense oligonucleotides (SPINRAZA® [nusinersen]), small molecules (EVRYSDI® [risdiplam]), and gene therapy (ZOLGENSMA® [onasemnogene abeparvovec]). Nonetheless, the therapeutic effect of the above therapies depends on the treatment initiation timings.
The study reported 2 cases of SMA-born infants in the same region. Patient 1 is a male infant born at 36 weeks and 2 days of gestation through the emergency cesarean section since his mother was diagnosed with premature rupture of membranes and placental dysfunction. The patient had 2 copies of SMN2 and was born NBS was initiated. Furthermore, he received onasemnogene abeparvovec therapy at the age of 4 months.
On the other hand, patient 2 was a male born at 42 weeks of gestation through a cesarean section. The patient reported no abnormalities during the gestation; his height was 51.5 cm. Moreover, he had no siblings. The patient was born with three copies of SMN2. The patient was diagnosed and treated with onasemnogene abeparvovec before the symptoms appeared.
Study results revealed that all reported patients with SMA having 2 copies of SMN2 and treated pre-symptomatically were able to sit without support before 12 months. In contrast, Patient 2 reported three copies of exon 7 of SMN2, which generally represent SMA type 2. This type of SMA usually develops at 6 to 18 months and is typically characterized by an inability to walk independently. The patient received onasemnogene abeparvovec therapy at 42 days and eventually acquired normal motor development and could walk independently at 11 months.
“Although the number of copies of SMN2 differed, our results suggest that the timing of gene therapy relative to symptom onset may be responsible for the difference in outcomes between Patient 1 and Patient 2,” the authors highlighted.
Treatment with onasemnogene abeparvovec is expensive. However, in Japan it is an insurance-approved treatment, and children with SMA can receive this treatment irrespective of the disease type. It is essential to administer it as soon as possible after birth to maximize its treatment effects. Moreover, NBS is significantly helpful in the early detection of SMA and is currently only available in limited areas in Japan.
“To obtain a considerable therapeutic effect, it is necessary to diagnose SMA as early as possible before symptoms appear and to initiate treatment,” the authors added.
SMA is a disease that causes muscle weakness and shrinkage due to the degeneration of anterior horn cells of the spinal cord.
Takaaki S, Kido J, Yukako Y, et al. Gene therapy for spinal muscular atrophy is considerably effective when administered as early as possible after birth. SSRN. Published online January 23, 2023.