Overview
Amelogenesis Imperfecta (AI), also known as Familial Enamel Hypoplasia (FEH), is a genetic disorder affecting tooth enamel in Japanese Akita Inu dogs. It causes misshapen, rough, and discoloured teeth due to inadequate enamel development. Both baby and permanent teeth are affected, with permanent teeth appearing small and pointed, with increased gaps between them.
The condition is caused by a mutation in the ACPT gene, which is inherited in an autosomal recessive pattern. Symptoms include poor enamel quality, where teeth are prone to attrition (wearing of the tooth surface), and brownish discolouration. The disease has no other health effects.
The single base insertion in the gene called ACP4 that causes Amelogenesis imperfecta in Japanese Akita Inu is autosomal recessive. This means that dogs that carry two copies of the mutation (homozygotes) will almost certainly develop General disease during their lives. Dogs that carry a single copy of the mutation (also known as carriers or heterozygotes) will not develop General disease as a result of the ACP4 mutation, but they will pass the mutation onto about half of any offspring they have. Breeding dogs that will not develop General disease should be the breeder’s priority, with a reduction in mutation frequency within the whole breed being the secondary, longer-term target.
Carriers can be bred from safely, provided they are mated to a dog that has also been tested and is clear of the ACP4 mutation (i.e. carry no copies of the mutation). If a carrier is mated to a clear dog approximately half of the resulting puppies will also be carriers, so should be tested themselves prior to breeding. Breeding carriers to tested, clear dogs is safe, in terms of avoiding dogs affected with Amelogenesis imperfecta, and will help to maintain the genetic diversity of a breed. It is therefore encouraged, particularly in the first few generations following the availability of a new genetic test, so that other desirable characteristics and traits can be preserved before the frequency of the disease mutation within the breed is gradually reduced.
