Amelogenesis Imperfecta (ENAM gene)

Amelogenesis imperfecta is a group of diseases that affect the integrity of tooth enamel. Among the genes that may be affected is ENAM, which is essential for tooth development.

Symptoms

Symptoms observed include gingivitis, plaque and tartar deposits. Dogs affected by this pathology lack normal hard and shiny tooth enamel, their permanent teeth are smaller and pointed. The surface of the crowns has a dull, rough, hypocalcified appearance, the ends of the crowns show abrasion and the dentin (the tissue underneath the enamel) may be exposed and become brownish in color. Perforations or cavities may appear in the enamel.

Disease Management

In dogs affected by amelogenesis imperfecta, special care should be taken to maintain good dental hygiene. In case your dog shows any symptoms, you should visit your veterinarian for evaluation.

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

Dental enamel is a mineralized tissue that covers the dental crown and is composed of hydroxyapatite crystals giving teeth their characteristic hardness and resistance to wear and fracture. Amelogenesis imperfecta (AI) comprises a group of clinically heterogeneous pathologies that affect the structure, composition and thickness of tooth enamel. The ENAM gene encodes for an enamelin protein which is a dental enamel matrix glycoprotein essential for the development of tooth enamel. Studies have shown that the presence of certain mutations affecting the ENAM gene can affect enamel development, such as the c.1991_1995delTTTCC deletion that was identified in Italian greyhounds suffering from AI.

Most affected breeds

Greyhound
Russell Terrier
Standard Poodle

Bibliography

Gandolfi B, Liu H, Griffioen L,et al. Simple recessive mutation in ENAM is associated with amelogenesis imperfecta in Italian Greyhounds. Anim Genet. 2013 Aug;44(5):569-78.

Hytönen MK, Arumilli M, Sarkiala E,et al. Canine models of human amelogenesis imperfecta: identification of novel recessive ENAM and ACP4 variants. Hum Genet. 2019 May;138(5):525-533.