Rare amber coat color in NFCs is caused by a single MC1R allele (a version of the gene) called "e,"

Below is a summary of a study which investigated the genetic cause of the rare amber coat of the Norwegian Forest Cat. It is very technical but it is hard to avoid its technicality 😢.

In a study researchers  sequenced the melanocortin 1 receptor (MC1R) gene in a group of cats with a yellow recessive coat color called amber, which is observed in Norwegian Forest Cats (NFCs) but apparently absent in other cat breeds. 

The researchers identified two single nucleotide polymorphisms (SNPs) in the coding sequence of the gene: one that causes a change in the amino acid sequence of the protein (a non-synonymous mutation) and one that does not (a synonymous mutation). They then genotyped a larger group of cats using PCR-RFLP (a method for analyzing DNA) and found that the non-synonymous mutation (c.250G>A) was present in all of the amber cats and not in any of the other cats. 

Dorian - picture copyright Crystalfjord Cattery

This mutation causes a change in the amino acid sequence of the protein, replacing an aspartic acid with an asparagine at position 84. The researchers also used 3D modeling to examine the structural changes caused by the mutation and found that it caused a modification in the electrostatic potential of the mutant protein. Based on these findings, the researchers concluded that amber coat color in NFCs is caused by a single MC1R allele (a version of the gene) called "e," which has not been previously documented.

Here is another picture of the beautiful amber NFC:

Dorian - picture copyright Crystalfjord Cattery