Amelogenesis Imperfecta Italian Greyhound Type (AI)
Amelogenesis Imperfecta Italian Greyhound type is a congenital teeth disorder also known as enamel hypoplasia in Italian Greyhounds. The disorder has strong resemblance to non-syndromic autosomal recessive amelogenesis imperfecta (AI) in humans.
Tooth enamel makes most of tooth tissue among humans and animals. It is a highly mineralized substance that has a role of a barrier to protect the tooth. In healthy teeth. Enamel is prone to degradation, when exposed to acids from food and drinks.
In humans, causes of defect of human enamel formation can be diverse, from prematurity, smoking or trauma, causing enamel hypoplasia in whole or a part of teeth. However, when caused by genetic factors, enamel hypoplasia occurs in all teeth in more uniform manner or even in other parts of body.
Amelogenesis Imperfecta in Italian Greyhound is affecting deciduous and permanent teeth and is manifested by enamel thinning and roughening or brownish mottling in areas of enamel thinning. It starts to develop in early adulthood of the dog. Teeth that are affected appear to be small and pointed with increased gaps. While amelogenesis imperfecta causes cavity in humans, this condition does not occur in dogs, due to maintained basic tooth structure throughout life. The disorder does not affect no tissues or organs other than teeth. Common symptoms occurring in Amelogenesis Imperfecta affected dogs are fever, nutritional disorders, trauma or infection.
Amelogenesis Imperfecta Italian Greyhound type is caused by a mutation in the enamelin (ENAM) gene. The mutation comprises a 5-bp deletion in exon 10 of the named gene. This mutation causes production of malfunctioning enamel proteins, such as amelogenin, enamelin, enamelysin and kallikrein-4.
AI is inherited in an autosomal recessive pattern. Healthy parents of an affected puppy are obligate heterozygotes, and therefore carry one mutant allele. Heterozygotes have no symptoms. Dogs homozygous for the mutation will display the symptoms of the amelogenesis imperfecta. At conception, each cub has a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of being unaffected and not a carrier.
Recently conducted research has revealed high carrier rate as well as high occurrence of affected dogs. While approximately half of dogs are unaffected (56%), 30% are carriers for the gene for amelogenesis imperfecta and 14% of the dogs are affected.