The Five Basic Colors The five basic color genes of mice are the following: · A – agouti locus · B – brown locus · C – albino locus · D – blue locus · P – Eye color locus The table below will explain the different genes and their effect on the color of a mouse.
The A Locus ~ Chromosome 2 ~ a
Symbol	Photo	Description
A		Agouti: The agouti gene is the so-called “wild type”. In other words, any wild caught mouse is most likely to have an agouti colored coat. The agouti gene is dominant and causes each strand of hair to have bands, or regions of color, with yellow, brown and black being the predominant colors.
A^vy		Viable Yellow. Homozygotes and Heterozygotes show much variation ranging from a clear yellow, to some brownish mottling, to agouti coloration. Their coats are more like the coat of an a/a mouse than agouti. More homozygotes than heterozygotes are clear yellow. This phenotype affects the amount of white in spotted varieties, usually resulting in less white than other varieties. Both homozygotes and heterozygotes tend to become obese, and this is directly related to the amount of yellow in their coat.
A^w		White Bellied Agouti: This gene is about the same as the Agouti gene except that the mouse has a white or light colored belly. This is a common mutation of the wild type, and can be used to get a chinchilla mouse, when combined with the chinchilla gene.
A^y		Yellow: In heterozygotes the hair is yellow, and the eyes are black. Homozygotes are not viable and die before implantation. As with the viable yellow allele, this gene is associated with obesity.
a		Non-Agouti: Removes the banding effect of the Agouti gene, leaving each strand of hair all one color.
a^e		Extreme Non-Agouti: This gene is responsible for the so-called “super black” mice. It eliminates any stray yellow strands of hair making the mouse a pure deep black color.
a^m		Mottled Agouti: This particular phenotype, when homozygous has a variable expression, anywhere from the extreme non-agouti to a normal agouti appearance. These mice are normally some in-between color, which is a mottling of yellow and black.
a^t		Tan: In this mutation the back is black, and the belly is cream or tan colored. This particular allele is dominant on the belly of the mouse, while it is recessive on the back of the mouse.

The B Locus ~ Chromosome 4 ~ Tyrp1^b
Symbol	Photo	Description
B		No Brown Dilution: This is the normal wild mouse color gene.
b		Brown dilution: This gene dilutes the black portion of mouse hairs into a brown color. When combined with the a gene the mouse will have strands of hair that are black from base to tip. Mice with this dilution have brown rather than black eyes.
b^c		Cordovan: This is a rich deep lustrous brown.

The C Locus ~ Chromosome 7 ~ Tyr^c
Symbol	Photo	Description
See the C-Locus paper for more information about this locus
C		Full Color: Mice with this gene have full color. There have been some reports of mice which are have a C/c combination. The reports state that mice with the albino allele are sometimes lighter in pigmentation than those who have a C/C makeup.
c		Albino: Hair and eyes are completely devoid of pigment. The pink-eyed effect is created by the blood vessels giving the mouse eyes a pink tinge. Homozygotes do not perform well on mouse intelligence tests, but this is surmised to be a fault of the lack of pigment in the retina, causing the mouse to have poor vision.
c^a		Acromelanic: This is fully recessive to wild-type genes, but dominant over c. Homozygotes are distinguishable from albino at birth due to the pigmentation of the eyes. They have pigmented eyes, ears, tail and anal region. Unlike the Himalayan variety, they do not have pigmented noses.
c^ch		Chinchilla. The chinchilla gene reduces the yellow in agouti coloration, and slightly reduces the black, giving agouti mice a silver coloration.
c^e		Extreme Dilution. Hair is very light gray and eyes are black. When crossed with c, the resulting offspring are almost white with black eyes.
c^h		Himalayan. In homozygotes, called Siamese, the first coat of hair is a uniform tan color. After the first molt, the ears, nose, tail and scrotum become dark like a Siamese cat. Eyes are slightly pigmented and appear red. Pigmentation is dependant on temperature. Mice raised in 15 degrees Celsius will show more pigmentation than mice raised in 30 degrees Celsius. When crossed with the c gene, the mice are called Himalayan and have near white bodies with only dark points.
c^r		Ruby-Eyed White: Homozygotes have reduced black pigment and no yellow pigment. They are lighter than homozygous chinchilla but darker than homozygous extreme dilution mice. Their eyes are ruby in adults.

The D Locus ~ Chromosome 9 ~ Myo5a^d
Symbol	Photo	Description
D		No Blue Dilution: This is the normal wild mouse color gene.
d		Blue. Originally called the Maltese Dilution, in nonagouti a/a mice, this recessive gene causes a blue dilution, causing the hairs to be blue or blue-black. This gene is closely linked to the short ear gene se.

The P Locus ~ Chromosome 7 ~ p
Symbol	Photo	Description
P		Black Eyes: Mice with this allele have black eyes. This is the wild type.
p		Pink Eyes: Mice with this allele have pink eyes. The eyes lack full pigmentation. This diluted pigmentation extends to the color of the strands of hair as well, diluting most of the colors, though yellow is only slightly diluted.

Genetics

[Mendelian Genetics | Beyond Mendel]

[The Five Basics | The Markings | Coat Consistency]

[Parts and Pieces | Genetic Mysteries]

Main Page

Agouti: The agouti gene is the so-called “wild type”. In other words, any wild caught mouse is most likely to have an agouti colored coat. The agouti gene is dominant and causes each strand of hair to have bands, or regions of color, with yellow, brown and black being the predominant colors.

White Bellied Agouti: This gene is about the same as the Agouti gene except that the mouse has a white or light colored belly. This is a common mutation of the wild type, and can be used to get a chinchilla mouse, when combined with the chinchilla gene.

Yellow: In heterozygotes the hair is yellow, and the eyes are black. Homozygotes are not viable and die before implantation. As with the viable yellow allele, this gene is associated with obesity.

Non-Agouti: Removes the banding effect of the Agouti gene, leaving each strand of hair all one color.

Extreme Non-Agouti: This gene is responsible for the so-called “super black” mice. It eliminates any stray yellow strands of hair making the mouse a pure deep black color.

Mottled Agouti: This particular phenotype, when homozygous has a variable expression, anywhere from the extreme non-agouti to a normal agouti appearance. These mice are normally some in-between color, which is a mottling of yellow and black.

Tan: In this mutation the back is black, and the belly is cream or tan colored. This particular allele is dominant on the belly of the mouse, while it is recessive on the back of the mouse.

No Brown Dilution: This is the normal wild mouse color gene.

Brown dilution: This gene dilutes the black portion of mouse hairs into a brown color. When combined with the a gene the mouse will have strands of hair that are black from base to tip. Mice with this dilution have brown rather than black eyes.

Cordovan: This is a rich deep lustrous brown.

See the C-Locus paper for more information about this locus

Full Color: Mice with this gene have full color. There have been some reports of mice which are have a C/c combination. The reports state that mice with the albino allele are sometimes lighter in pigmentation than those who have a C/C makeup.

Acromelanic: This is fully recessive to wild-type genes, but dominant over c. Homozygotes are distinguishable from albino at birth due to the pigmentation of the eyes. They have pigmented eyes, ears, tail and anal region. Unlike the Himalayan variety, they do not have pigmented noses.