Mice homozygous for this spontaneous recessive mutation are recognized by a diluted coat color that appears chocolate brown. This color dilution also lightens the eyes, feet, ears, and tail of affected animals.
The chtl2J re-mutation of chtl arose spontaneously on the B6.V-Lepob/J strain at The Jackson Laboratory in 1997 when that strain was at N24F1. A chtl2J homozygous female from this intercross was bred with an unaffected sibling and homozygotes were produced. This strain has been maintained by sibling breeding homozygotes with heterozygotes, of either gender, and in 2005 reached generation F25. Obese mice (Lepob homozygotes) have never been found in this chocolate like 2 Jackson subline.
|Allele Name||chocolate-like 2 Jackson|
|Gene Symbol and Name||chtl, chocolate-like|
|Strain of Origin||B6.Cg-Lepob/J|
|General Note||Tests for allelism to cht and chtl were considered inconclusive because the F2s produced in both tests resulted in two coat colors, and while indicating some interaction between the new mutation and the chocolate mutation, does not prove that the new mutation is a remutation to chocolate.|
|Molecular Note||This spontaneous mutation occurred at The Jackson Laboratory.|