Online Mendelian Inheritance in Man (OMIM^®) is a continuously updated catalog of human genes and genetic disorders and traits, with particular focus on the molecular relationship between genetic variation and phenotypic expression. It is thus considered to be a phenotypic companion to the Human Genome Project. OMIM is a continuation of Dr. Victor A. McKusick's Mendelian Inheritance in Man, which was published through 12 editions, the last in 1998. OMIM is currently biocurated at the McKusick-Nathans Institute of Genetic Medicine, The Johns Hopkins University School of Medicine.

Each OMIM entry is given a unique six-digit number as summarized below:

1----- (100000- ) 2----- (200000- ) Autosomal loci or phenotypes (entries created before May 15, 1994)

3----- (300000- ) X-linked loci or phenotypes

4----- (400000- ) Y-linked loci or phenotypes

5----- (500000- ) Mitochondrial loci or phenotypes

6----- (600000- ) Autosomal loci or phenotypes (entries created after May 15, 1994)

Allelic variants (mutations; see 1.4) are designated by the MIM number of the entry, followed by a decimal point and a unique 4-digit variant number. For example, allelic variants in the factor IX gene (300746) are numbered 300746.0001 through 300746.0101.

An asterisk (*) before an entry number indicates a gene.

A number symbol (#) before an entry number indicates that it is a descriptive entry, usually of a phenotype, and does not represent a unique locus. The reason for the use of the number symbol is given in the first paragraph of the entry. Discussion of any gene(s) related to the phenotype resides in another entry(ies) as described in the first paragraph.

A plus sign (+) before an entry number indicates that the entry contains the description of a gene of known sequence and a phenotype.

A percent sign (%) before an entry number indicates that the entry describes a confirmed mendelian phenotype or phenotypic locus for which the underlying molecular basis is not known.

No symbol before an entry number generally indicates a description of a phenotype for which the mendelian basis, although suspected, has not been clearly established or that the separateness of this phenotype from that in another entry is unclear.

A caret (^) before an entry number means the entry no longer exists because it was removed from the database or moved to another entry as indicated.

See also the description of symbols used in the disorder column of the OMIM Gene Map and Morbid Map.

Mutations are cataloged in OMIM in the Allelic Variants section of gene entries (see 1.2). For most genes, only selected mutations are included. Criteria for inclusion include the first mutation to be discovered, high population frequency, distinctive phenotype, historic significance, unusual mechanism of mutation, unusual pathogenetic mechanism, and distinctive inheritance (e.g., dominant with some mutations, recessive with other mutations in the same gene). Most of the allelic variants represent disease-causing mutations. A few polymorphisms are included, many of which show a positive correlation with particular common disorders.

The OMIM Gene Map and Morbid Map present the cytogenetic locations of genes and disorders, respectively, that are described in OMIM. Only OMIM entries for which a cytogenetic location has been published in the cited references are represented in the Gene Map and Morbid Map.

The OMIM Gene Map can be searched by gene symbol (e.g., "SOD1"), chromosomal location (e.g., "5", "1pter", "Xq" ), or by disorder keyword (e.g., "alzheimer").

Brackets, "[ ]", indicate "nondiseases," mainly genetic variations that lead to apparently abnormal laboratory test values (e.g., dysalbuminemic euthyroidal hyperthyroxinemia).

Braces, "{ }", indicate mutations that contribute to susceptibility to multifactorial disorders (e.g., diabetes, asthma) or to susceptibility to infection (e.g., malaria).

A question mark, "?", before the disease name indicates an unconfirmed or possibly spurious mapping.

The number in parentheses after the name of each disorder indicates the following: (1) the disorder was positioned by mapping of the wildtype gene; (2) the disease phenotype itself was mapped; (3) the molecular basis of the disorder is known; (4) the disorder is a chromosome deletion or duplication syndrome. Move the cursor over the number to display this information.

Please use the form available at the Contact Us tab at the top of the page.

It is usually most appropriate to cite the actual journal article for the data of interest.

Citing OMIM as a whole:

Online Mendelian Inheritance in Man, OMIM^®. McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University (Baltimore, MD), {date}. World Wide Web URL: http://omim.org/

Citing a specific entry in OMIM:

Online Mendelian Inheritance in Man, OMIM^®. Johns Hopkins University, Baltimore, MD. MIM Number: {MIM number}: {Date last edited}: . World Wide Web URL: http://omim.org/

Citing an OMIM entry for personal communication:

{Authors};{Date}. Personal Communication in OMIM^® Online Mendelian Inheritance in Man. MIM Number: {MIM number} Johns Hopkins University, Baltimore, MD. World Wide Web URL: http://omim.org/

Citing the printed version of MIM:

McKusick, V.A.: Mendelian Inheritance in Man. A Catalog of Human Genes and Genetic Disorders. Baltimore: Johns Hopkins University Press, 1998 (12th edition).

OMIM.org can be optimally viewed using Firefox 2.0+, Google Chrome and Internet Explorer 7.0+ on Microsoft Windows; Firefox 2.0+, Google Chrome, Safari 4.0+ on Mac OS X; Firefox 2.0+ on Linux.

OMIM curation and updating is funded by a grant from the National Human Genome Research Institute (NHGRI) [1U41HG006627]. Initial development of the OMIM.org website was supported by Johns Hopkins Medicine and a grant from the Maryland Department of Health and Mental Hygiene. OMIM is hosted at University of California Santa Cruz (UCSC) Genome Bioinformatics.

The OpenHelix Blog has a short video tutorial on OMIM.

OMIM's primary website is available at http://omim.org/ and a mirror site is available at http://us-east.omim.org/.

OMIM uses genomic reference build GRCh37 (Patch 5) available at ftp://ftp.ncbi.nih.gov/gene/DATA/gene2refseq.gz (181 MB file).