HPO Get Term Hierarchy

Get the parent or child terms of an HPO phenotype term in the ontology hierarchy. HPO is organized as a directed acyclic graph (DAG) where more specific phenotypes are children of broader terms. Use direction='children' to find more specific sub-phenotypes, or direction='parents' to find broader categories. Example: children of HP:0001250 (Seizure) include 'Bilateral tonic-clonic seizure', 'Focal-onset seizure', 'Febrile seizure', and others. Parents include 'Abnormal nervous system physiology'.