Helpful hints for understanding strain and gene nomenclature
JAX® Mice are named according to the guidelines set by the International Committee on Standardized Genetic Nomenclature for Mice, and strain names are revised as necessary to conform to these guidelines.
Nomenclature for Genetically Engineered Mice
Nomenclature for chemically-induced and targeted mutations follow the same guidelines as described for mice with spontaneous mutations (see “Nomenclature for Mice with Spontaneous Mutations”). Alleles are designated either by the chemical mutagen or by the abbreviation “tm” (targeted mutation), followed by a number and the laboratory registration code, and selection criteria superscripted to the gene symbol (e.g., Apoa1tm1Unc).
Nomenclature for Mice with Spontaneous Mutations
Gene symbols are italicized. Symbols for recessive genes begin with a lower case letter, and symbols for dominant, semi-dominant, and co-dominant genes begin with an uppercase letter, followed by lower case letters. The gene and allele symbols for mutant genes are the same until the gene is cloned (see “Nomenclature for Cloned Mutations,” below). Different alleles of a gene may be represented by a superscript to the gene symbol. Nomenclature for a strain with a spontaneous mutation is as follows: C57BL/6J-Aw–J. When a mutation is maintained on an inbred strain background by mating homozygotes together, the gene symbol is given once. All offspring are affected mutants (phenotypically manifest the genetic mutation).
Nomenclature for Cloned Mutations
In 1994, the International Committee on Standardized Genetic Nomenclature for Mice voted to superscript a mutation’s symbol to the cloned gene symbol. For example, the shiverer (shi) mutation in the myelin basic protein (Mbp) gene becomes Mbpshi. If the original mutation symbol already has a superscript, the mutation and allele superscript symbols are placed on one line in the new superscript and hyphenated. For example, the myelin deficient (shimld) mutation becomes Mbpshi–mld). When a mutation occurs in a cloned candidate gene, the first letter of the gene symbol may remain uppercase, and the inheritance pattern may be conveyed in the allele symbol. For example, the recessive yellow (e) and sombre (Eso) alleles of the melanocortin 1 receptor (Mc1r) gene become Mc1re and Mc1rE–so. Mutant allele names stay the same. In this catalog, we list the previous symbol and cross-reference to the new symbol. Former gene symbols are listed under symbol common names in the strain detail. For a complete listing of nomenclature rules and guidelines, see www.informatics.jax.org/mgihome/nomen.
Nomenclature for Coat Color Markers
Some strains (e.g., strains carrying the diabetes mutation, such as BKS.Cg-m +/+ Leprdb/J) are maintained by using coat color markers. Leprdb is maintained in repulsion with the closely linked marker misty, m, a coat color gene. The mating system we use, +/+ Leprdb x m +/+ Leprdb, produces three phenotypically distinguishable genotypes: + Leprdb/+ Leprdb mice, which are fat and black; m +/+ Leprdb mice, which are lean and black; and +/m + mice, which are lean and misty.
Nomenclature for Congenic Strains
Congenic strains are designated by a compound symbol consisting of the host strain (usually abbreviated), a period, the donor strain (also usually abbreviated), a hyphen, and the italicized symbol of the differential locus or loci and allele(s) (e.g., B10.129P-H12b). When the donor strain either is not an inbred or is complex, the symbol “Cg,” denoting congenic, is used. Congenic nomenclature is applied to incipient as well as to full congenics. The generation number is included in the strain detail.
The genetic background of many congenics is a mixture of C57BL/6J and a 129 substrain (designated either B6;129, B6;129P, or B6;129S; see explanation that follows on “Revised Nomenclature for Strain 129 Mice”). However, the backgrounds of some congenic strains are unknown, derived from more than two progenitor strains, or have genetic contributions from an unknown or outbred source. The background of such congenics is frequently designated as “STOCK.” Formerly, most spontaneous and induced mutations transferred by backcrossing from a mixed background (e.g., either B6;129 or STOCK) to an inbred background were not described by conventional congenic nomenclature. However, many JAX® GEMM® strain names have been revised to more clearly indicate the origin of a mutation (e.g., B6.129P2-Apoetm1Unc/J).
The Jackson Laboratory supplies a large number of histocompatibility congenic strains. In some cases, multiple lines are derived from the same donor strain and are distinguished by a number and/or letter in parentheses (e.g., B10.129P-H11b(10M)/SnJ and B10.129P-H46b H47b(21M)/Sn).
Revised Nomenclature for Strain 129 Mice
Because 129 substrains are genetically different from each other, (Simpson et al. 1997), they must be clearly distinguished. For your convenience, this catalog contains both the updated and former 129 strain designations. For detailed information on the 129 nomenclature standards, please see “Nomenclature for Strain 129 Mice” (JAX Bulletin #1, 1999, revised June 2001). Also, see our “Interactive tutorial on mouse nomenclature.”
References
Simpson EM, Linder CC, Sargent EE, Davisson MT, Mobraaten LE, Sharp JJ. 1997. Genetic variation among 129 substrains and its importance for targeted mutagenesis in mice. Nat Genet 16:19-27.
