Test Detail

Feline agouti colour (tabby pattern, with hair bands and a pale belly) depends on the Agouti locus (ASIP). The recessive non-agouti allele (a) prevents the production of functional ASIP protein and results in a solid-coloured coat (black, blue, chocolate or cinnamon depending on the other loci), whereas the agouti alleles allow the banded pattern. It is a colour trait, not a disease.

Common allele in the domestic cat and present in many breeds; the frequency of a/a varies according to breed and pattern selection. Breed-specific figures: limited data.

- Agouti pattern: light and dark bands in the hair (tabby) and a paler belly
- Non-agouti allele (a/a): solid-coloured coat without agouti bands
- No clinical or pathological manifestations

The Agouti locus was described in the cat in the mid-20th century. The molecular basis of the non-agouti allele (a) was identified when Eizirik et al. (2003) demonstrated that a 2-bp deletion in the ASIP gene produces a truncated protein lacking the C-terminal active domain, explaining melanism not associated with MC1R. This allele is the classic cause of solid coat and the absence of agouti banding. The domestic cat shows a wide variety of alleles at the locus, some with influence from other felid species.

- Solid colour is an aesthetic trait, not a defect or a disease.
- To preserve the agouti pattern, avoid mating two solids (a/a); to obtain solids, mate two carriers or a solid with a carrier.
- Knowing the genotype of the breeding animals helps plan the pattern of the litter.
- Do not over-select for a single pattern if this reduces the genetic variability of the breed.

Differential diagnosis with melanism from other causes (gain of function in MC1R) and with the different tabby patterns. The non-agouti allele is identified by the c.123_124del deletion. Interpretation must integrate the other colour loci; the result is not a diagnosis of disease.

1. Eizirik E et al. 2003. Molecular genetics and evolution of melanism in the cat family. Current Biology. PMID: 12620197
2. Lyons LA. 2015. DNA mutations of the cat: the good, the bad and the ugly. Journal of Feline Medicine and Surgery. PMID: 25701860
3. OMIA:000201-9685. Coat colour, agouti in Felis catus. Online Mendelian Inheritance in Animals.