SMN1 and spinal muscular atrophy, type 1: At the time of this study, the c.835-3C>A intragenic mutation was identified in a Japanese patient with SMA type 1 (SMN1, exon 7 one copy, exon 8 one copy) with a severe phenotype despite having two copies of SMN2 [12]; SMN transcript analysis showed that SMN1 exon 7 was deleted, indicating that the c.835-3C>A intragenic mutation does affect the splicing of exon 7.