Cat Blog - Everything about felines!
Find helpful cat articles that are easy to understand with detailed information. Did you know that cats are known to be the most hygienic animals of all, they are self-cleaning? You can information like this on or cat blog.
Inhibitor Gene - Dominant Cat Trait
Melanin inhibitor gene is a dominant gene. This means a non-expressing cat can not carry this gene . Offspring can receive this gene from either parent but only if one or both parent has the gene. The Inhibitor gene has a greater affect on the yellow pigment phaeomelanin than on black pigment eumelanin.
Silver vs. Smoke
Agouti cat + Inhibitor gene = Silver
Non-agouti cat + Inhibitor gene = Smoke
What is tarnish?
The Inhibitor gene removes varying degrees the yellow pigment from the hair shaft. Yellow pigment still showing through is often referred to as “tarnish” or “tarnishing”. This yellow pigment can cause a “dirty” coat look or “rust” color. Breeding silver to silver color will produce little to no tarnishing.
| smoke | aa I- | - | For "I-" you can either have II (homozygous for silver) or Ii (heterozygous for silver) |
| silver shaded | A- I- |
plus genes for tabby | For "A-" you can either have AA or Aa. For "I-" you can have II or Ii. Note that silver tabby, shaded and shell have the same genetic code for their coat colour. |
| silver shell | A- I- |
||
| silver tabby | A- I- Ta- ticked |
For "Ta-" you can have TaTa, or
Tata. You find TaTa f.e. in the Somali or Abyssinian. |
|
| A- I- Mc- mackerel |
For "Mc-" you can have McMc or
Mcmc. Note: You may add Ta- or tata to this code. |
||
| A- I- mcmc blotched |
Resources
http://www.eurocatfancy.de/en1/nav/cat-genetics/gene_I.html
http://rfwclub.org/Silver.htm
Health Resources
Recommendation by Drs. Mark Kittleson, Rebecca Gompf, and Susan Little
Veterinary Cardiac Genetics Lab - A genetic test has been developed for the cMyBP-C mutation causing HCM in Maine Coons. Information about HCM and instructions to order the test kit.
Frequently Asked Questions about the test for the HCM Mutation.
Feline Hypertrophic Cardiomyopathy by Jody Chinitz, Marcia Munro, and Dr. Mark Kittleson
Feline Cardiomyopathies by Dr. Paul Pion
Hypertrophic Cardiomyopathy in Cats by PetPlace
ACVIM Specialty of Cardiology (Alphabetic and Geographic lists of veterinary cardiology diplomates)
Cat Modes of Inheritance
Autosomal Dominant Inheritance
For an autosomal dominant disorder, only one copy of a given allele is necessary to produce the trait. If an animal receives an abnormal allele from one parent and a normal allele from the other parent, the abnormal trait will be expressed.
Autosomal Recessive Inheritance
With an autosomal recessive genetic disorder, an animal must receive two copies of the abnormal gene (one from each parent) in order to show signs of the disorder. In most situations, this occurs when both parent animals are asymptomatic carriers of the disorder.
Because the disorder is recessive, an animal who carries one copy of the abnormal gene and one copy of the normal gene will not show signs of disease. If two parents who are carriers are bred, however, 25% of their offspring will receive two abnormal copies of the gene and thus express the genetic disorder. Another 50% of their offspring will receive one abnormal copy of the gene and thus be genetic carriers of the disorder. Finally, 25% of their offspring will receive two normal copies of the gene and be unaffected.
Sex-linked Inheritance
Sex-linked health conditions in cats primarily involve chromosome abnormalities that can lead to issues like sterility, abnormal development, and other genetic disorders. A key example is male calico or tortoiseshell cats, which have an extra X chromosome (XXY) that causes sterility and may be associated with Klinefelter's syndrome. Disorders of sex development (DSDs), where an animal's chromosome complement doesn't match its physical appearance, also fall under this category.
Common sex-linked conditions
Male calico/tortoiseshell cats: These cats have two X chromosomes and one Y chromosome (XXY), which makes them male but gives them the orange and black/brown patches normally found on females. The XXY configuration typically leads to sterility and can cause other health issues.
Klinefelter's syndrome: This is the condition associated with the XXY chromosome arrangement in male cats, similar to humans.
Turner's syndrome: This occurs when a cat inherits only one X chromosome (XO) and can be lethal due to incomplete genetic information.
Disorders of Sex Development (DSDs): This broad category includes genetic conditions where an animal's sex chromosomes do not align with its physical development.
Examples of DSDs: These can include a variety of conditions, such as ambiguous genitalia, enlarged clitorises in XX females, undescended testicles in XY males, or other congenital malformations.
Causes: DSDs can be caused by sex chromosome abnormalities (like XXY or XO), XX or XY sex chromosomes with internal mutations, or mosaicism, where a cat has both XX and XY cells.
Sex-linked orange coat color mutation: The gene for this orange/red coat color is located on the X chromosome, which is why it's most commonly seen in females (tortoiseshells and calicos) that have two X chromosomes. This mutation is a sex-linked trait that is expressed through X-inactivation in females.