SMN2 and spinal muscular atrophy: This study aims to describe longitudinal clinical outcomes among Romanian children with spinal muscular atrophy who have received early and sustained disease-modifying therapies in order to investigate the impact of SMN2 copy number, timing and type of therapeutic intervention and comprehensive supportive care on both motor and respiratory functions, as well as to analyze the development and transformation of SMA phenotypes within the context of widespread newborn screening and the adoption of innovative treatment strategies.