Faulty Tooth Enamel Formation Amelogenesis imperfecta (AI) is a disorder of faulty tooth enamel formation that involves 2 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 AI allele (A), the severity of the disorder is determined by mutations in a gene carried on the X chromosome. The non-severe allele (X^N) is dominant over the severe allele(Xⁿ). In the absence of the autosomal dominant allele (A), the abnormality gene on the X chromosome is not expressed.   In other words, individuals that are homozygous recessive for AI are normal, no matter what allele they have on the X chromosome.  Question: A woman with normal teeth had four children with a man with the non-severe form of AI as follows:

a boy without amelogenesis imperfecta, a girl without amelogenesis imperfecta a boy with severe amelogenesis imperfecta a boy with non-severe amelogenesis

 

Identify the parental genotypes. (1 mark) Complete the Punnett square for the parental cross, and identify the possible phenotype ratios of the children. (2 marks)