Ichthyosis (type 2, Golden Retriever)

Gene: ABHD5

Transmission: Autosomal recessive

For an autosomal recessive genetic disease an animal must have two copies of the mutation in question to be at risk of developing the disease.  Both parents of an affected animal must be carriers of at least one copy of the mutation.  Animals that have only one copy of the mutation are not at risk of developing the disease but are carrier animals that can pass the mutation on to future generations.

Mutation: Deletion, ABHD5 gene; c.1006_1019 del., p.(D336S fs STOP 6), exon 7, chromosome 23

Medical system: Skin

Breeds: Golden Retriever

Age of onset of symptoms: (not reported)

Ichthyosis is the name given to a heterogeneous group of skin diseases seen in dogs, with both genetic and environmental causes. Ichthyosis is characterized by abnormal differentiation (keratinization) of the epidermis resulting in dry, scaly skin; “ichthy-” refers to fish, as in fish scales.  Dogs with ichthyosis present clinically with large, thick, white to grey scales on the skin that can even spread to the inside of the auricle.  The scales are composed of flakes of dead skin and can be powdery to adherent. Clinical signs may also include hyperpigmented skin.  The genetic disease cannot be cured, but symptoms can be treated throughout the dog’s life by administering topical treatments. The best treatment for the breed is prevention through genetic testing of breeding animals to identify carriers.

The Golden Retriever now has two genetic causes of ichthyosis. The most common and traditional form is caused by a mutation in the PNPLA1 gene (Ichthyosis, Golden Retriever type). The form identified more recently is associated with a mutation in the ABHD5 gene (Ichthyosis, type 2 Golden Retriever), seems to give more severe symptoms, but with a disease more restrained in frequency, associated with a pedigree in North America.

References:

OMIA link: [2368-9615]

Kiener S, Wiener DJ, Hopke K, et al. (2022) ABHD5 frameshift deletion in Golden Retrievers with ichthyosis. G3 (Bethesda) 12(2):jkab397.  [pubmed/34791225]

Mauldin EA, Elias PM. (2021) Ichthyosis and hereditary cornification disorders in dogs. Vet Dermatol 32:567-e154. [pubmed/34796560]

Contributed by: Ellycia Manata and Maxine Aubin, class of 2027, Veterinary Medicine Faculty, University of Montreal.  (Translation: DWS).