Homozygous expression of a Fars2 mutation (p.Asp142Tyr), which severely compromises mt-PheRS aminoacylation activity and causes hereditary spastic paraplegia in humans, is embryonically lethal in mice during early gestation, at a similar timepoint to Fars2 knockout mice (Yang et al., 2016; Chen et al., 2022). The gene discussed is FARS2; the disease is hereditary spastic paraplegia.