Recent studies have demonstrated that deficiencies in METTL1 or WDR4 abolish tRNA m7G modifications, leading to various pathological conditions, including impaired self-renewal and differentiation of embryonic stem cells [35], microcephalic primordial dwarfism [36], and Galloway-Mowat syndrome [37]. This evidence concerns the gene WDR4 and Galloway-Mowat syndrome.