Spinal muscular atrophy is characterized by the degeneration of spinal motor neurons. This autosomal recessive disorder is due to mutations in the SMN1 gene. Different therapeutic strategies have been developed using different targets. The first target is SMN2 which remains present in patients but the SMN2 transcripts differ from those of SMN1 by alternative splicing of exon 7. One of the therapeutic approaches aims at reducing the exon 7 jump of SMN2 using antisense oligonucleotides. Our objective is to determine if there is a correlation between clinical benefit, SMN2 copy number, and RNA splice correction by in vivo quantification of splice correction of SMN2.