To ascertain whether mutant mice carrying the SMN2 gene, like SMA patients, present pathological phenotypes, we additionally generated SMN2 2-copy Smn1ΔMPC (Prrx1Cre; Smn1f7/f7; SMN2+/+) and SMN2 1-copy Smn1ΔMPC (Prrx1Cre; Smn1f7/f7; SMN2+/0) mice. Here, SMN2 is linked to proximal spinal muscular atrophy.