SMN1 and proximal spinal muscular atrophy: Remarkably, in a recent study by Kim et al., the pathogenic SMA phenotype was almost completely reversed back to normal in mice with a lack of a functional SMN1 gene but the presence of single nucleotide variant in the gene Hspa8, leading to G470R amino-acid substitution in the heat shock protein 70 (HSPA8) protein encoded by this gene [63].