Online Mendelian Inheritance in Man (OMIM®), currently in its 55th year, is a foundational resource in human
genetics and genomics. OMIM's goal is to expand the understanding of human biology and disease by
providing a timely, authoritative, easily accessible, and computable knowledgebase of the increasingly complex
and nuanced relationships between human genes and genetic disorders and traits. OMIM serves diverse
scientific communities, including clinical geneticists, health care providers, basic, model organism, translational
and clinical researchers and bioinformaticians as well as educators and students in these fields. OMIM.org is
accessed by over 25,000 unique daily users worldwide. OMIM's core mission is the naming and classification
of Mendelian phenotypes (traits and diseases) and the relationship of the phenotypes to the genes that cause
them. This is accomplished by expert review, evaluation, and summary of the peer-reviewed biomedical
literature by an expert staff of biocurators and MD and PhD science writers who have decades of experience in
synthesizing and incorporating substantive information into rich, structured gene and phenotype entries,
comprehensive clinical synopses, and a GeneMap/Morbid Map from which Phenotypic Series are created. As
of 31 December 2020, OMIM includes over 25,692 entries, 7,754 clinical synopses, and 489 Phenotypic
Series. MIM numbers are internationally recognized as unique identifiers of Mendelian disorders and appear
throughout the biomedical literature. OMIM entries and clinical synopses are mapped to controlled-vocabulary
resources such as ICD10, SNOMED, HPO, and the UMLS. These mappings are searchable and available
through the API to facilitate computational survey and data mining, as well as the functional integration of
OMIM data to enhance analysis pipelines, dissemination, and computability. In addition, OMIM leverages data
from a variety of other resources to augment its unique content and collaborates with other informatics
resources and curation efforts such as ClinVar, ClinGen, and the Monarch Initiative to harmonize data content.
To broaden and improve OMIM as the preeminent resource for the clinical, academic, and commercial
research community, we have expanded our current coverage by adding expert scientific and bioinformatics
staff and will continue to enhance its structural compatibility with other entities, maintain industry best practices
in database and software development, and provide Web Services and REST API in a targeted and cost-
effective way. We will augment efficient and automated processes to mine the biomedical literature in the
curation process and introduce new data visualizations and search functions. To further optimize the end-user
experience, we have experienced user support staff to provide technical assistance and training. We regularly
solicit feedback and community input to improve the functional features and free accessibility of our resource.
OMIM is an essential resource for clinical medicine, model organism research, and disease gene and
therapeutic discovery.