Onset The age group in which disease manifestations appear. HP:0003618 HP:0003674 HP:0003597 HP:0003630 MSH:D017668 UMLS:C0206132 HP:0003590 HP:0011007 Adolescent is defined by WHO as a person between 10-19 years of age. HP:0003603 HP:0003626 HP:0003628 Age of onset HP:0003588 HP:0003602 HP:0003668 HP:0003663 HP:0003664 human_phenotype Age symptoms begin Clinical course