Pathogenic variants in the FGF12 gene leading to a gain‐of‐function mechanism and partial duplication encompassing the FGF12 gene leading to a loss‐of‐function mechanism are associated with developmental and epileptic encephalopathy (DEE), characterized by developmental delay, intellectual disability, ataxia, and drug‐resistant epilepsy. This evidence concerns the gene FGF12 and Global developmental delay.