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COLOUR GENETICS - G locus

The G gene - GREYING - does exactly what it says. It turns the hair grey, much in the same manner as premature greying hair in humans. As greying progresses, coloured hair is replaced with silver, white or colourless hair. The more greying there is, the lighter the dog appears. Greying may start shortly after birth or may not begin until much later. A dog with an active greying gene will display a coat which has a gradual accumulation of white/colourless hairs interspersed with the coloured hairs. Greying appears to affect colour with incomplete dominance. Not all Havanese grey, some do not. The greying gene is often confused with the silvering gene "V" but is not the same. While "V" filters colour development, "G" softens colour over time by greying the coat.

Remember that E can be brown as well as black. Although only the black variations are shown here, all the same possibilities exist in brown.

dog displays greying [ GG ] This Havanese has two copies of the dominant greying gene. Dog will progressively grey as it matures.
Phenotype - progressively greying coat
Genotype - [ GG ]

dog displays greying [ Gg ] This Havanese carries one copy of the dominant greying gene and one copy of the recessive non-greying gene. The dog will progressively grey as it matures but to a lesser extent than the dog with a double dose of the dominant gene.
Genotype - progressively greying coat
Phenotype - [ Gg ]

dog displays dark colour [ gg ] : The recessive non-greying gene causes little or no premature greying.
Phenotype - dog displays dark coat colour
Genotype - [ gg ]