Researchers generated stable transgenic lines expressing the wild-type or mutant version of a gene of interest, such as the ALS-causative G348C mutation in TDP-43 (Lissouba et al., 2018) or the C1315Y mutation in COL2A1 associated with lethal fetal skeletal dysplasia (Zhang et al., 2021). The gene discussed is COL2A1; the disease is skeletal dysplasia.