Orphon
An orphon is a gene identified in a chromosomal location outside the main loci.
- IG orphons are localized outside the three main loci IGH, IGK and IGL [1].
- TR orphons are localized outside the four main loci TRA, TRB, TRG and TRD [2].
An orphon is either pseudogene or ORF. It is not functional.
By extension, an orphon is an instance of the 'gene' concept of IMGT-ONTOLOGY [3].
Orphons belonging to a same group and localized on a same chromosome constitute a 'chromosomal orphon set'.
Note:
The term orphon was introduced by Childs et al. [4] to refer to
"genetic elements that have lost their families". It was first applied to solitary members
of histone and ribosomal gene families PMID: 6784929.
References:
[1] Lefranc, M.-P. and Lefranc, G.,
The Immunoglobulin FactsBook,
Academic Press, 458 pages (2001) ISBN: 012441351X
[2] Lefranc, M.-P. and Lefranc, G.,
The T cell receptor FactsBook,
Academic Press, 398 pages (2001) ISBN: 0124413528.
[3] Giudicelli, V. and Lefranc, M.-P., Bioinformatics, 15, 1047-1054 (1999)
PMID: 10745995, LIGM:221
[4] Childs, G. et al., Cell, 23, 651-663 (1981)
PMID: 6784929