A Agouti (ASIP) Tan points (at/at) = tricolor is common. Sable (Ay) present but less dominant in breed than tan points. Dominant Common ›
B Brown (TYRP1) bb = "Red" (liver/chocolate). AKC standard color in Australian Shepherds. Very common. Common ›
D Dilute (MLPH) Dilute (dd) Aussies exist but are non-standard. Rare in the breed. Rare
E Extension (MC1R) Em (mask) present. ee (recessive red) rare in the breed. Recessive Common
K Black (CBD103) Beta-defensin 103 (CBD103) locus, also called the K locus or dominant black locus. Three alleles in a strict dominance hierarchy: KB (dominant black) > kbr (brindle) > ky (allows Agouti expression). KB is a gain-of-function mutation that constitutively activates eumelanin production, overriding the Agouti locus entirely. A dog with at least one KB allele will be solid eumelanin (black or brown depending on B locus) regardless of Agouti genotype. kbr produces brindle striping: alternating eumelanin and phaeomelanin stripes over Agouti-determined base color. Brindle expression requires at least one kbr allele and no KB allele. ky/ky allows full Agouti locus expression — this is required for fawn, sable, tricolor, tan point, and wild sable phenotypes to be visible. K locus is dependent on E locus: if ee (recessive red), K locus genotype has no visible effect because eumelanin cannot be produced in the coat. Recessive Common ›
I Intensity (MFSD12) Major facilitator superfamily domain containing 12 (MFSD12) locus, also called the I locus or Intensity locus. Controls the intensity of phaeomelanin (red/yellow) pigment. Wild-type I/I produces full-intensity red/yellow phaeomelanin. The In (intensity dilution) variant, when homozygous (In/In), dilutes phaeomelanin from deep red/orange to pale cream or white. MFSD12 functions as a lysosomal transmembrane transporter affecting phaeomelanin synthesis. Crucially, Intensity only affects phaeomelanin — eumelanin (black/brown) is NOT affected. This means a dog can be In/In and still have a fully black nose and eye rims while having cream/white coat color in phaeomelanin areas. The degree of dilution varies between breeds and individuals, ranging from cream to solid white in ee dogs with In/In. Heterozygous N/In dogs are carriers and typically show little to no dilution. Line-specific ›
M Merle (PMEL) Merle is AKC STANDARD. Blue merle and red merle are two of the four standard colors for "merle australian shepherd." Common ›
