Epidermolytic hyperkeratosis (ichthyosis)

 

Gene: KRT10

Transmission: Autosomal

Mutations:

Norfolk Terrier mutation (recessive): Substitution (splicing error), KRT10 gene; c.1125+1 G>T, intron5

Chihuahua mutation (dominant): Substitution, KRT10 gene; c.437 G>A, p.(R146H)

Breeds: Chihuahua, Lucas Terrier, Norfolk Terrier

Age of onset of symptoms: From birth

Ichthyosis refers to a family of skin diseases that disrupt normal skin structure and function and give a scaly appearance to the skin.  “Ichthy-” refers to fish, as in fish scales.  Ichthyosis is a very common condition in the canine population with both genetic and environmental contributing factors.  The Norfolk Terrier ichthyosis is epidermolytic meaning that blisters are present.  The skin of affected dogs is very fragile, and wounds and ulcers are formed at birth at sites of friction.  The skin also becomes hyperpigmented (black with time) at friction sites.  The mutation reported for the chihuahua is from a case report involving  severe ichthyosis with dominant genetics.

 

References:

OMIA link: [1415-9615]

Donner J, Freyer J, Davison S, et al. (2023) Genetic prevalence and clinical relevance of canine Mendelian disease variants in over one million dogs.  PLoS Genet. 19(2):e1010651 [pubmed/36848397]

Kiener S, Åhman S, Jagannathan V et al. (2023) Heterozygous KRT10 missense variant in a Chihuahua with severe epidermolytic ichthyosis.  Anim Genet. [pubmed/37332248]

Credille KM, Barnhart KF, Minor JS, Dunstan RW (2005) Mild recessive epidermolytic hyperkeratosis associated with a novel keratin 10 donor splice-site mutation in a family of Norfolk terrier dogs. British Journal of Dermatology. 153 (1), 51-58. [pubmed/16029326]

Barnhart KF, Credille KM, Ambrus A, Dunstan RW. (2004) A heritable keratinization defect of the superficial epidermis in norfolk terriers. J Comp Pathol. 130(4):246-54. [pubmed/15053927]