Reference no: EM131995164

Faulty Tooth Enamel Formation

Amelogenesis imperfecta (AI) is a disorder of faulty tooth enamel formation that involves two genes. 

The expression of AI disorder is determined by mutations in an autosomal gene. One copy of the mutated allele (A) will cause the disorder. Thus the expression of AI disorder is inherited in an autosomal dominant pattern. 

In individuals that have the autosomal dominant allele the severity of the disorder is determined by mutations in a gene carried on the X chromosome. The non severe  (X^N) allele is dominant over the severe (Xⁿ) allele. In the absence of the autosomal dominant allele, the abnormality gene on the X chromosome is not expressed. 

Question 

A woman with normal teeth had four children with a man with non-severe form of AI:

• A boy was born without amelogenesis imperfecta
• A girl was born without amelogenesis imperfecta 
• A boy was born with severe amelogenesis imperfecta
• A boy was born with non severe amelogenesis imperfect