Hypocatalasia

Acatalasemia or hypocatalasia is a rare genetic disease that arises as a result of the absence of catalase activity, which causes the appearance of oral lesions. The CAT gene is responsible for encoding catalase, therefore, any mutation or deficiency in this gene can lead to the development of acatalasemia.

Symptoms

About 50% of dogs affected by acatalasemia have clinical symptoms that manifest mainly in the oral cavity, such as painful gum sores, tooth loss and oral gangrene. In addition, this condition can also affect carbohydrate, lipid and homocysteine metabolism, and increase the risk of diabetes mellitus and arteriosclerosis.

Disease Management

Treatment of acatalasemia focuses on maintaining proper oral hygiene and the use of antibiotics to treat recurrent infections. In addition, mouth rinses can be used to help minimize oral pain.

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

Acatalasemia occurs due to a lack of activity of the enzyme catalase, which is encoded by the CAT gene. Catalase plays a key role in the body's defense against oxidative stress by catalyzing the breakdown of hydrogen peroxide into water and oxygen. This reaction is crucial for the proper functioning of red blood cells, liver and other tissues exposed to oxidative stress. The condition is related to a nonsense mutation in the CAT gene. The c.979G>A substitution produces a change from alanine to threonine, resulting in a mutant protein that is more susceptible to proteolytic degradation in reticulocytes.

Most affected breeds

American Foxhound
Beagle

Bibliography

Nakamura K, Watanabe M, Takanaka K,et al. cDNA cloning of mutant catalase in acatalasemic beagle dog: single nucleotide substitution leading to thermal-instability and enhanced proteolysis of mutant enzyme. Int J Biochem Cell Biol. 2000 Nov-Dec;32(11-12):1183-93.