Albinism

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Albino puli (genotype cc)[1]

Albinism is an autosomal-recessive genetic disease of dogs characterized by absence of melanin in the coat and irises.

Cream or white is a relatively common coat color in many breeds but the underlying genetic mechanism for this color has not been elucidated. Many Labrador Retrievers, of the type that were known as 'yellow labs', are often more cream than yellow. Likewise some Golden Retreivers are more cream than golden.

This disease is caused by a tyrosinase-related protein 1 deficiency (tyrosinase-negative)[2].

Tyrosinase-positive albino dogs also occur, commonly seen in Akita, bernese Mountain Dog, Miniature Schnauzer, Hungarian Puli, West Highland White Terriers, Samoyed and German Shepherd breeds.

Affected dogs have characteristic pale pink skin, white hairs and pink eyes. Tyrosinase-positive dogs have a very pale cream or gray color to the coat hairs.

Homozygous (CC or cc) and heterozygous (Cc) albino genes are responsible for albinism in dogs. Forms of phenotypic expression include:

  • Allele CC - full color - allows full expression of whatever pigment is prescribed by other genes. Most dogs are CC.
  • Allele Cch - chinchilla - When present in double dose removes most or all of the phaeomelanin pigment with only a slight or no effect on black pigment. Black and silver mudis indicate presence of the gene.
  • Allele Cce - extreme dilution - gene may be part of the makeup of some "white" dog breeds where the white color is due to extreme dilution of tan. Bleaches up the ee-red dogs.
  • Allele cc - albino - cc individual cannot produce any melanin pigment, white with red eyes, lips, nose and eye rims.

High tyrosinase expression is found in all canine melanomas and melanocytic tumors[3].

References

  1. Kennel Kilvan
  2. Prohaska JR (1986) Genetic diseases of copper metabolism. Clin Physiol Biochem 4(1):87-93
  3. Phillips JC et al (2012) Evaluation of tyrosinase expression in canine and equine melanocytic tumors. Am J Vet Res 73(2):272-278