To test whether incomplete rescue of Mtrfr leads to activation of the ISR, RT-qPCR from liver and spinal cord samples was performed looking at two genes associated with the ISR in other mouse models of peripheral neuropathy: fibroblast growth factor 21 (Fgf21) and growth differentiation factor 15 (Gdf15). This evidence concerns the gene FGF21 and peripheral neuropathy.