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Gene Information

Genetic Alterations
Spontaneous mutation
Genotype Determination
Ashiness animals appear normal as juveniles. By two months of age, some animals destined to become ashy develop paler than normal ankles above the typical white foot. There may be early depigmentation of the skin at the distal end of the rostrum that leaves a pigmented spot at the tip. Progression of the trait follows a predictable pattern: Between 80 and 120 days the first appearance of gray hairs on the rostrum occurs, and gray begins to extend upward on the limbs, but some animals are still undistinguishable. By 120 - 180 days more than 90% of the homozygotes show some graying on the muzzle and base of the tail. At 6 - 9 months virtually all animals exhibit some manifestation of the trait. Gray on the rump and rostrum becomes more prominent and extensive. The area of graying tends to extend backward from the face, forward from the rump and upward on the legs with each successive molt. The interscapular region of the back is the final area to lighten. By 9 - 12 months most homozygotes show a distinctly "ashy" overall aspect. The face and rump are mostly white, but the dorsum is partially pigmented. Many ashiness animals do not progress beyond this stage, but some continue to lose pigment until the animal is virtually all white. The eyes remain fully pigmented. The trait appears to be due to inactivation of melanocytes. Limited pigmentation can be restored with melanocyte-stimulating hormone (MSH).
MeSH Terms
  • Aging/genetics
  • Animals
  • Chi-Square Distribution
  • Crosses, Genetic
  • Drug Implants
  • Female
  • Hair Color/drug effects
  • Hair Color/genetics
  • Male
  • Melanocytes/drug effects
  • Mutation
  • Peromyscus/genetics
  • Phenotype
  • alpha-MSH/administration & dosage
  • alpha-MSH/pharmacology
Strain Development
Source: About 1960. University of Oregon. Ashiness segregated from a stock of P. m. rubidus taken near Alsea Bay, OR.
Primary Reference

Teed SK., Crossland JP, and Dawson WD. Coat color genetics of Peromyscus. I. Ashiness, an age-dependent coat color mutation in the deer mouse. J Hered. 1990 Jul-Aug;81(4):309-13. (Medline PMID: 2177072)

For more information, please see Ashiness on the Peromyscus Genetic Stock Center website.

Colony and Husbandry Information

Colony Surveillance Program and Current Health Reports

For more information about this colony's health status contact
Coat Color
Homozygous (ahy/ahy) age dependent mutant that begins early depigmentation at around 80 days of age. The trait appears to be due to inactivation of melanocytes.

Heterozygous (ahy/+): The same a wild-type


MMRRC Breeding System
Not applicable; only cryopreserved sperm is available. The parent colony was sufficiently large to use a random breeding scheme
Breeding Scheme(s)
Not applicable; only cryopreserved sperm is available; mice cryorecovered (see below) can be bred Wild-type female x Wild-type male
Overall Breeding Performance
Peromyscus mice breed best in a 16:8 light / dark cycle.
Average litter size
Recommended wean age
25 days

Order Request Information

Male mice were obtained from the Peromyscus Genetic Stock Center as part of a long term project to develop cropreservation techniques for Peromyscus. Sperm have been cryopreserved and are available. However, cryorecovery techniques have yet to be developed.

Distribution of this strain requires submission of the MMRRC Conditions of Use (COU). A link to the COU web form will be provided via email after an order has been placed; the form should be completed then or the email forwarded to your institutional official for completion.

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