Agouti, ASIP (A locus)
The agouti signalling peptide (ASIP) is responsible for phaeomelanin production (red pigment) and is associated with melanism (black/brown markings) in the coat. A homozygous mutation in the ASIP gene causes solid coat colour (non-agouti coat) in felines. “a” is autosomal recessive, requiring two copies of the mutant allele(s) to confer solid colour. The charcoal colour in Bengal’s is caused by a compound heterozygote (APbe/a) of the leopard cat agouti allele (APbe) and the non‐agouti allele (a).
Chocolate, TYRP1 (B Locus)
The B locus or Tyrosinase Related Protein TYRP1 gene is associated with eumelanin production. B is the wild type for the mutation, which corresponds to eumelanin production. Chocolate coats are denoted by (bb).
Cinnamon, TYRP1 (B Locus)
The B locus or Tyrosinase Related Protein TYRP1 gene is associated with eumelanin production. B is the wild type for mutation, which corresponds to eumelanin production. Cinnamon coats are denoted by (bibi).
Burmese, TYR (C Locus)
The C locus is also called the albino series locus. While encoded by the tyrosinase (TYR) gene, mutations in this locus are associated with temperature dependent colour and albinism. Albinism is a genetic condition characterised by the lack of pigment in the coat, skin, and eyes, however, is associated with some disorders. The alleles associated with the coat colours are as follows:
C (full colour) > cb (Burmese) = cs (Siamese) > c (albino)
All these traits are autosomal recessive and require two copies of the mutant allele to present with the coat change.
Siamese Point, TYR (C Locus)
The C locus is also called the albino series locus. While encoded by the tyrosinase (TYR) gene, mutations in this locus are associated with temperature dependent colour and albinism. Albinism is a genetic condition characterised by the lack of pigment in the coat, skin, and eyes, however, is associated with some disorders. The alleles associated with the coat colours are as follows:
C (full colour) > cb (Burmese) = cs (Siamese) > c (albino)
All these traits are autosomal recessive and require two copies of the mutant allele to present with the coat change.
Dilution, MLPH (D Locus)
Melanophillin (MLPH) is a protein, required for the transportation of melanin between or within melanosomes. Mutation(s) in the MLPH gene reduces the distribution of eumelanin and phaeomelanin resulting in a dilute phenotype. “D” represents non-dilute and presents with intense colour. “d” is recessive, and “dd” represents dilute colour.
Amber, MC1R (E Locus)
The Melanocortin 1 receptor (MC1R) or extension (E) locus is encoded by the MC1R gene, which determines the distribution of eumelanin (black to brown) within the coat of the feline and determines the colour of the cat’s nose. This locus has two described mutations that affect the distribution of eumelanin within the coat.
Long Hair
Fibroblast growth factor 5 is a protein encoded by the FGF5 gene. FGF5 acts as a key signalling molecule to initiate the transition from hair growth to regression phase. Disruption of this gene or protein function results in extension of the growth cycle and produces long hair. There are 4 mutations associated with functional disruption of the FGF5 gene in felines. Long hair is inherited in an autosomal recessive manner; thus, two copies of a mutant allele are required to confer long hair.
