SMN2 and proximal spinal muscular atrophy: Furthermore, the hnRNP A1 inhibits exon 7 inclusion during gene splicing by binding both ESSs at exon 7 and ISS N1 at intron 7 of SMN2, that suppressing the regulatory effects of hnRNP A1 on SMN2 alternative splicing leads to a functional protein with exon 7 inclusion beneficial in treating spinal muscular atrophy (Kashima et al., 2007a; Beusch et al., 2017).