Ultra-early treatment initiated at 9 days of age for spinal muscular atrophy: a case report

Introduction Spinal muscular atrophy (SMA) requires ultra-early therapeutic intervention to optimize motor outcomes. Particularly for infants with two copies of SMN2 , treatment initiation within 14 days of age is critical. However, outsourcing a confirmatory test after a positive newborn screening (NBS) result often leads to significant delays. We aimed to establish a rapid in-house digital PCR (dPCR) diagnostic system to facilitate pre-symptomatic treatment within this critical timeframe. Case report A male infant with no family history of SMA was referred at 8 days of age after a positive NBS result. An ISO 15189-accredited in-house dPCR assay identified homozygous deletion of SMN1 and three copies of SMN2 within 11 hours of sample receipt, establishing a definitive diagnosis. Risdiplam was initiated at 9 days of age, followed by onasemnogene abeparvovec at 27 days. CHOP INTEND scores increased from 53 at treatment initiation to 56 at 25 days. Assay validation showed complete concordance with certified copy numbers and inter-assay coefficients of variation below 4%. Conclusions This case suggests that a rapid in-house dPCR workflow can shorten the time from a positive NBS result to definitive diagnosis and may facilitate treatment within the early therapeutic window.