SMN2 and proximal spinal muscular atrophy: Expectedly, the liver’s mRNA expression of IGF pathway genes, reported to be decreased in SMA mouse models and patients (Hua et al., 2011; Murdocca et al., 2012; Deguise et al., 2021; Sahashi et al., 2013), showed no difference when comparing controls to SMN2 1-copy Smn1ΔMPC mutants (Figure 2D).