Amelogenesis imperfecta (AI) is a disorder of faulty tooth enamel formation. It is inherited in an autosomal dominant and X-linked dominant pattern.
Amelogenesis imperfecta (AI) is a disorder of faulty tooth enamel formation. It is inherited in an autosomal dominant and X-linked dominant pattern.
The expression of AI disorder is determined by mutations in the autosomal alleles. One copy of the mutated allele (A) will cause the disorder. The severity of the disorder is determined by mutations in a gene carried on the X chromosome. Normal (or non-severe) abnormality (XN) is dominant over the abnormality (or severe) (Xn) allele. In the absence of the autosomal dominant allele, the abnormality gene on the X chromosome is notexpressed.
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 imperfecta
- Identify the parental genotypes.
- Complete the Punnett square for the parental cross, and identify the possible
phenotypic ratios of the children.
HINT: This question is a dihybrid cross involving an autosomal gene and an X-linked gene.
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