Genetic basis of Amelogenesis Imperfecta - in Akita dogs is caused by a recessive mutation in the ACPT gene (also known as ACP4), specifically a c.1189dupG frameshift mutation. The ACPT gene encodes acid phosphatase involved in enamel formation and development of teeth. The mutation leads to defective enamel production during tooth development. This disorder is inherited in an autosomal recessive manner: affected dogs have two copies of the mutated gene; carriers have one copy and show no disease but can pass the mutation to offspring. Genetic testing using cheek swabs or blood samples can identify clear, carrier, and affected dogs.
Pathophysiology - The mutation disrupts the function of the ACPT protein essential for normal enamel mineralization and tooth development. This leads to enamel hypoplasia or hypomineralization with thinning, roughening, and brownish mottling of the enamel on both deciduous and adult teeth. Affected teeth are often smaller, pointed, brittle, and have increased spacing between them. The enamel defects make teeth more prone to wear but do not appear to increase the risk of cavities or systemic health issues.
Complications - Affected dogs display abnormal tooth enamel which may cause dental discomfort or increased wear. Teeth appearance is notably altered (small, pointed, gaps, rough surfaces), which can affect chewing efficiency. There are no reported systemic or health complications beyond the enamel defect. Early recognition by veterinary dentists or genetic testing can prevent misdiagnosis.
Why This Matters to Breeders and Vets - For breeders, knowledge of carrier status is crucial to avoid producing affected puppies by preventing carrier-to-carrier matings. For veterinarians, understanding and diagnosing AI helps in advising owners about dental care and management of affected dogs. Genetic testing facilitates accurate diagnosis and informed breeding decisions to reduce incidence in the population. Maintaining breed dental health and avoiding production of affected dogs improves welfare and breed quality.
Summary - Amelogenesis Imperfecta (Akita Type) is an autosomal recessive genetic disorder caused by a frameshift mutation in the ACPT gene, resulting in defective tooth enamel formation. Affected Akitas have thin, roughened, brownish enamel, small, pointed teeth with increased spacing, but no systemic health problems. Genetic testing is key for diagnosis and to guide breeders in avoiding affected offspring, thereby improving dental health and welfare in the breed.