Epidemiology of Spinal Muscular Atrophy Based on the Results of a Large-Scale Pilot Project on 202,908 Newborns

Background This study presents the findings of a newborn screening (NBS) pilot project for spinal muscular atrophy (SMA) 5q in multiple regions across Russia for a period of 2022 year. The aim was to assess the feasibility and reproducibility of NBS for SMA5q in diverse populations and estimate the real prevalence of SMA5q in Russia as well as the distribution of patients with different number of SMN2 copies. Methods The pilot project of NBS here was based on data, involving the analysis of 202,908 newborns. SMA screening assay was performed using a commercially available real-time PCR kit, the Eonis SCID-SMA. Results In one year, 202,908 newborns were screened, identifying 26 infants with homozygous deletion of SMN1 exon 7, yielding an estimated SMA5q incidence of 1:7804 newborns. 38.46% had two SMN2 copies, 42.31% had three copies, 15.38% had four copies, and 3.85% had five copies SMN2. Immediate treatment was proposed for patients with two or three SMN2 copies. Infants with four or more SMN2 copies warranted further investigation on management and treatment. Short-term monitoring after gene therapy showed motor function improvements. Delays in treatment initiation were observed, including the testing for AAV9 antibodies and non-medical factors. Conclusions The study emphasizes the need for a standardized algorithm for early diagnosis and management through NBS to benefit affected families. Overall, the NBS program for SMA5q in Russia demonstrated the potential to improve outcomes and transform SMA from a devastating disease to a chronic condition with evolving medical requirements.