The identification of 15 individuals from 13 families with biallelic ZNF808 variants and permanent neonatal diabetes conclusively established causality, as per the guidelines set out by MacArthur et al.2All the individuals with biallelic ZNF808 variants described by De Franco et al.1had low birthweight and early onset of insulin-dependent diabetes, consistent with severe insulin deficiency pre- and postnatally.3 Here, ZNF808 is linked to type 1 diabetes mellitus.