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. Author manuscript; available in PMC: 2023 Jan 4.
Published in final edited form as: Am J Med Genet C Semin Med Genet. 2022 Jul 24;190(2):231–242. doi: 10.1002/ajmg.c.31989

Figure 2. Prenatal onset terms.

Figure 2.

The HPO provides terms to denote the range of onset of diseases or phenotypic features. New terms were added for more granularity in the prenatal period. Prenatal ages are shown as gestational weeks, which are defined as the time from the last menstrual period of the mother. For instance, Embryonal onset refers to a disease or phenotypic feature that is first observed in the 8 weeks following fertilization, which corresponds to 10 weeks of gestation (WG). 13 WG + 6D refers to a gestational age of 13 weeks and 6 days.