Phenotype names should be unique, enhance clinical care and classification, and be easy to communicate. Acronyms and eponyms can both serve in this capacity. When a phenotype is determined to be new to OMIM, it is assigned a number and name. If the same or similar phenotype exists in OMIM but the phenotype is caused by mutation in a different gene, the existing name is retained, followed by a serial number, and the phenotype is added to the Phenotypic Series. If the phenotype is not similar to one in OMIM, three to five of the most clinically significant features are used to create an acronym or initialism that is both informative and memorable; or, if the features are too numerous or variable, an eponym is chosen, using the names of the authors who first described or established the phenotype–gene connection, thereby ligating the eponymous phenotype to the paper(s) that described it.
