A gene represents a major concept of classification in IMGT. A gene is defined as a DNA sequence that can be potentially transcribed and/or translated (this definition includes the regulatory elements in 5' and 3', and the introns, if present). The IMGT gene definition follows that given in . A gene is "a hereditary unit that, in the classical sense, occupies a specific position within the genome or chromosome; a unit that has one or more specific effects upon the phenotype of the organism; a unit that can mutate to various allelic forms; a unit that recombines with other such units".
Instances of the "gene" concept are gene names. By extension, orphons and pseudogenes are also instances of the "gene" concept.
IMGT/GENE-DB is based on the 'gene' concept.
Below are listed a selection of links to IMGT Scientific chart, IMGT Repertoire, IMGT Education and IMGT Posters and diaporama which provide information on immunoglobulin (IG) and T cell receptor (TR) genes, on major histocompatibility (MH) genes, and on genes encoding related proteins of the immune system (RPI), members of the IgSF and MhSF.