Ichthyosis (gen PNPLA1, Golden Retriever)

Ichthyosis is a disease that damages the stratum corneum of the epidermis causing the skin to thicken and flake and, consequently, increasing the risk of skin infections in affected dogs.

Symptoms

Puppies affected by ichthyosis have abnormal skin at birth. The skin is rough and covered with thick, greasy scales, some of which adhere tightly to the skin and coat, and some of which flake off in scales. The paw pads may thicken and cause pain. The disease usually worsens with age and becomes chronic and severe for life. No other symptoms affecting other tissues are observed.

Disease Management

Currently, there is no cure for ichthyosis in dogs. Management of the disease focuses on alleviating the symptoms and improving the animal's quality of life and requires ongoing care and veterinary follow-up. If you suspect that your dog may be affected by this disease, it is important to take him to a veterinarian for advice on the most appropriate treatments. Possible treatments include mild anti-seborrheic shampoos, moisturizers and synthetic retinoids.

Genetic basis

This disease follows an autosomal recessive mode of inheritance. Autosomal recessive inheritance means that the dog, regardless of sex, must receive two copies of the mutation or pathogenic variant to be at risk of developing the disease. Both parents of an affected dog must carry at least one copy of the mutation. Animals with only one copy of the mutation are not at increased risk of developing the disease, but may pass the mutation on to future generations. Breeding between dogs carrying genetic variants that can cause disease, even if they do not show symptoms, is not recommended.

Technical report

In dogs, several mutations associated with ichthyosis have been detected that are breed-specific and follow an autosomal recessive mode of inheritance. In Golden Retrievers it has been shown that the mutation responsible for ichthyosis is in the PNPLA1 gene (patatin-like phospholipase domain containing 1). This gene produces a protein involved in lipid metabolism and is expressed in the keratinocytes of the epidermis, where it plays a role in the metabolism of glycerophospholipids in the skin barrier.

Most affected breeds

Golden Retriever

Bibliography

Grall A, Guaguère E, Planchais S,et al. PNPLA1 mutations cause autosomal recessive congenital ichthyosis in golden retriever dogs and humans. Nat Genet. 2012 Jan 15;44(2):140-7.