Congenital Cornification (Discovered in the Chihuahua)

Congenital Cornification, also known as inflammatory linear verrucous epidermal nevi (ILVEN) in humans, is an X-linked dominant disorder characterized by sharply demarcated alopecia, hyperkeratosis (thickening of the outer layer of skin), brown-black scaling, and dilated, keratin-filled follicles that can appear in stripes over the head, trunk and limbs in a distinct patterning known as Blaschko’s lines. The lesions appear shortly after birth and can be quite painful. Secondary skin infections are common in affected individuals, and paw pad hyperkeratosis can lead to significant lameness. Affected dogs may also show stunted growth based upon clinical signs with other variants in the same gene. Histological examination can reveal hyperplastic epidermis, hyperkeratosis and parakeratosis while the follicular infundibula may appear distended with parakeratotic keratin. Unfortunately, this disorder is likely lethal in affected males, with death predicted to occur in utero or shortly after birth (with mouse models showing abnormally thin placental tissue and fewer blood vessels). Thus, current research describes affected females as having one copy of the X-linked variant. More research is needed to understand the possibility of and effects on females with two copies of this variant.

There is no cure for this disorder. Diagnosis and treatment of secondary skin infections is important. Topical therapy with cholesterol (e.g. lovastatin) and glycolic acid creams has improved lesions in one documented canine case and is used in human cases of ILVEN. Therapies for hyperkeratosis may include shampoos, emollients, moisturizing sprays and, in some cases, a diet high in fatty acids. Good skin hygiene may help prevent secondary infections, and pain relief may be warranted for some cases.

There are many responsibilities to consider when breeding dogs. Regardless of test results it is important that your dog is in good general health and that you are in a position to care for the puppies if new responsible owners are not found. For first time or novice breeders, advice can be found at most kennel club websites.

This disorder is X-linked dominant, meaning the genetic variant is found on the X chromosome. However, since it is dominant in nature, males and females only require one copy of the variant to be at an elevated risk for being diagnosed with this condition. Due to the severity of the disorder, use of dogs with one or two copies of the Verrucous Epidermal Keratinocytic Nevi variant are not recommended for breeding, as there is a risk that the resulting litter will contain affected puppies. Please note: It is possible that clinical signs similar to the ones associated with the Congenital Cornification (Discovered in the Chihuahua) variant could develop due to a different genetic or clinical cause.