There were 71 (94.67 %) SMA patients with homozygous deletion on SMN1 among 75 SMA patients; 6 SMA patients with a homozygous deletion of NAIP (exon 4 and exon 5), 3 SMA patients with a homozygous deletion of NAIP (exon 4) and 3 SMA patients with a homozygous deletion of GTF2H2 (exon 10). Here, SMN1 is linked to proximal spinal muscular atrophy.