Genetics
The munchkin gene is an autosomal dominant one. Homozygous embryos for the munchkin gene are not viable due to gene lethality. Only kittens that are heterozygous for the munchkin gene develop into viable short legged munchkin kittens. Because only heterozygous munchkin cats are able to pass on the gene, all litters with at least one munchkin parent have the possibility of containing kittens with the phenotypes: short-legged or normal-legged (referred to as non-standard munchkin), with the genotypes of Mm or mm, where M is the trait for short legs and m is the trait for long legs. A litter with two munchkin parents, Mm x Mm, have the chance of producing these offspring: 25% MM- a nonviable kitten, 50% Mm-short-legged, 25% mm- normal.
Punnett squares, in which the M represents the dominant munchkin gene and the m represents the recessive normal gene, may be used to illustrate the chances of a particular mating resulting in a short-legged cat.
Kittens bearing two copies of the munchkin gene (MM) will not survive. Kittens bearing one munchkin gene and one normal gene (Mm) will be short-legged munchkins. Kittens bearing two normal genes (mm) will be normal. Mm munchkin kittens will be able to pass on the munchkin gene to their own offspring. Normal mm kittens will not, as they do not have a copy of the munchkin gene.
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For each kitten born from this mating, there is a 25% chance it will not survive, a 25% chance it will be normal, and a 50% chance it will be short-legged. |
| For each kitten born from this mating, there is a 0% chance it will be non-viable (unless it has a different, unrelated condition), a 50% chance it will be normal, and a 50% chance it will be a munchkin. |
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Read more about this topic: Munchkin (cat)