The transgenic SMA mouse strain used in this study, also known as the Taiwanese SMA mouse, can produce two types of SMA mice: the severe SMA‐I mice that carry two copies of human SMN2 gene and have an average lifespan of 10 days; and the mild SMA‐III mice that carry 4 copies of human SMN2 gene which have a normal lifespan, and the only phenotype of tail and ears necrosis commencing at approximately 3 weeks old.24 This evidence concerns the gene SMN2 and proximal spinal muscular atrophy.