Do domestic cats have a mutation where heterozygotes for the allele of this mutation do not? - briefly
Yes, domestic cats exhibit several mutations where heterozygotes do not display the phenotype. One notable example is the mutation responsible for the polydactyl trait, where cats with one copy of the allele have an extra digit, but the phenotype is not always expressed in heterozygotes.
Do domestic cats have a mutation where heterozygotes for the allele of this mutation do not? - in detail
In the realm of feline genetics, certain mutations can exhibit unique patterns of inheritance and expression. One such phenomenon is known as codominance or incomplete dominance, where heterozygotes express a distinct phenotype that is different from either of the homozygous genotypes. This can occur in domestic cats, leading to observable traits that are not merely a blend of the two alleles but rather a unique combination.
Codominance is a type of inheritance where both alleles of a gene pair are fully expressed in the heterozygote. A classic example in cats is the coat color pattern known as tortoiseshell. This pattern arises from the X-linked O (orange) locus, where the alleles for black (B) and orange (O) fur are codominant. Female cats, which are heterozygous for these alleles (B/O), exhibit patches of both black and orange fur. Male cats, having only one X chromosome, typically do not show this pattern unless they have a genetic anomaly such as Klinefelter syndrome (XXY), which allows for the expression of both alleles.
Incomplete dominance, on the other hand, results in a phenotype that is intermediate between the two homozygous phenotypes. An example in cats is the coat color known as chinchilla. This color pattern is the result of a dilution gene that affects the distribution of pigment in the fur. Heterozygous cats for this gene have a diluted coat color that is neither fully colored nor fully white, but a blend of the two.
Another intriguing example is the Manx cat, which is known for its lack of a tail. This trait is the result of a semi-dominant mutation that affects the development of the spine. Heterozygous Manx cats may have a shortened tail or no tail at all, while homozygous cats for this mutation often have severe spinal deformities and are typically stillborn or die shortly after birth.
In summary, domestic cats do exhibit mutations where heterozygotes express distinct phenotypes. These can range from codominant traits like tortoiseshell patterns to incomplete dominance seen in chinchilla coat colors, and semi-dominant traits like the tailless condition in Manx cats. Understanding these genetic mechanisms is crucial for breeders, veterinarians, and researchers, as they provide insights into feline genetics and the inheritance of specific traits.