 GPx4 differs from the other GPx family members in terms of its monomeric structure, a less restricted dependence on glutathione as reducing substrate, and the ability to reduce lipid-hydroperoxides inside biological membranes.Inactivation of GPX4 leads to an accumulation of lipid peroxides, resulting in ferroptotic cell death.Mutations in GPX4 cause spondylometaphyseal dysplasia.