While the HPO includes ways to encode age-based features within broad categories such as “neonatal onset” or “childhood onset”, a more nuanced approach may be necessary to identify differences such as the later onset of Dravet syndrome when caused by variants in PCDH19 rather than SCN1A [10]. Here, SCN1A is linked to encephalopathy, progressive, early-onset, with brain edema and/or leukoencephalopathy.