The Genetics of Red

PLEASE NOTE: These genetics articles  were written by Mindy Ferreira, and are the sole property of the author including the tables that were developed.

Red is a sex linked gene. The red gene is only carried on the x (female) chromosome. All females are xx, where as males are xy. Each cell during development "turns off" the coding for one of the x chromosomes in every  female. This on/off is random... as is evident in the random speckles and spots in the torties. In the cells where one x chromosome has the red gene and the other x chromosome does not, those cells that have the chromosome carrying red "turned on"  will be red, the cells that have the chromosome carrying red "turned off" will be seal. This is how a female that has one red gene Oo will be a tortie. A female that has two red genes will be red OO, It does not matter which chromosome is turned on or off in each cell... since they both have the red gene. Since males are the combination of one x chromosome and one y chromosome, they only need one red gene to be red. There is not the issue of one chromosome being inactivated since the males are xy not xx.

Red is produced when a biochemical process substitutes the eumelanin (black and all derived colors) with phaeomelanin as the hair is developing. That gives a lighter pigment grain which we perceive as red. Another fact with the red is that both tabby (agouti) (A) and solid (non-agouti) (a) look the same.  The non-agouti (a) gene works by depositing eumelanin on the ends of all the hair shafts, "filling in" the background with the same color as the dark stripes. The tabby stripes then disappear.  In a red cat, there is no eumelanin produced.  The tabby markings can not disappear. This explains why reds always show pattern, but may never produce agouti kittens. To improve the color density, appearance of no stripes and shade of red, you must manipulate the group of modifiers, which are better known as polygenes. They are responsible for the deep red color, and what appears to be a lack of striping.

In this table, we are just looking at the inheritability of the red gene. The color of the non-red offspring will be any color that could be expected from the sire and dam.

MALE MALE
Red non-red
O o
FEMALE Tortie Oo males:
50% Red 
O
males:
50% Red
O
males:
50% non-red
 o
males:
50% non-red
o
females:
50% Red
OO
females:
50% non-red
oo
females:
50% Tortie 
Oo
females:
50% Tortie
 Oo
MALE MALE
Red non-red
O o
FEMALE Red OO  males:
100% Red
O
males:
100% Red
O
females:
100% Red 
OO
females:
100% Tortie
Oo
MALE MALE
Red non-red
O o
FEMALE non-red oo females:
100% Tortie
Oo
males:
100% non-red
o
males:
100% non-red
o
females:
100% non-red
oo

 

 

 

 

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