He et al investigated the copy number changes in theSMN2,NAIP,GTF2H2, andH4F5genes in 157 SMA patients and found that theSMN2gene copy number was 8.72% single copy, 73.83% two copies, 15.43% three copies, and 2.01% four copies. This evidence concerns the gene NAIP and proximal spinal muscular atrophy.