E-locus extension / Amber (MC1R-related) - Norwegian Forest Cat

E-locus extension / amber in cats

This genetic test detects the MC1R variant c.250G>A, the amber allele at the E locus. The trait is also known as amber, extension, E locus or, in some descriptions, X-Colour. The allele is especially known in the Norwegian Forest Cat.

What does amber mean?

Amber affects the balance between dark eumelanin pigment and reddish phaeomelanin pigment. Kittens may be born dark and become warmer amber in colour later. In dilute cats the colour can appear lighter, and patterns such as tabby can still influence the final look.

Why this test is useful

• The test shows whether the cat is clear, a carrier or genetically amber for the MC1R variant.
• Breeders can plan amber combinations and explain unexpected colour development more accurately.
• The result helps combine amber with other coat-colour results such as D locus and agouti/tabby.

Amber is inherited as autosomal recessive: one copy means carrier status, while two copies cause the amber phenotype.