If she inherits two copies of the orange gene she will be orange (ginger).ĭuring embryonic development of the female kitten, one of the X chromosomes is switched off to prevent the expression of both X chromosomes. If she inherits one copy of orange, and one copy of non-orange (black or chocolate), she will be tortoiseshell. The female can inherit one copy of the orange gene or two copies. The male can only inherit one copy of the orange ( O) gene and if he does, will be orange. The O gene converts the production of black pigment (eumelanin) into orange (phaeomelanin). Male cats have one X and one Y chromosome (XY) while females have two X chromosomes (XX). The orange gene ( O) is located on the X chromosome and is dominant to non-orange. Each gene comes in a pair, one from the mother and one from the father. Chromosomes and genes Designua/ShutterstockĪ gene is a basic unit of inheritance that determines the cat’s traits. The black, chocolate, grey or lilac areas of the tortoiseshell cat are non-agouti. In the case of the tortoiseshell cat, the non-agouti gene is a recessive gene responsible for producing hair that is a uniform colour instead of the typical banded hair shaft seen in tabbies. We have pointed cats, dilute, sworls, spots, curly coats and cats with white patches. The wild-type coat colour and pattern is a brown mackerel tabby but genetic mutations have occurred that have led to changes to the cat’s coat pattern and colour. In some cats, there will be more red than black, which is known as a reverse tortie. The most common colour combination is black and red, which consists of almost equal amounts of black to red. This unusual coat pattern is sex-linked and is almost exclusively found in female cats. A tortoiseshell cat is a cat with a coat colour made up of mottled patches of black, chocolate or grey along with red or cream.

Tortoiseshell cat and calico cat