In order to determine the inheritance pattern, analyze the presence of affected individuals and patterns of inheritance in the pedigree.
In order to determine whether pedigrees are compatible with autosomal dominant, autosomal recessive, or X-linked dominant and X-linked recessive inheritance, we need to analyze the patterns of inheritance seen in the pedigree. Here are the characteristics of each type of inheritance:
Autosomal Dominant:
- All affected individuals have at least one dominant allele.
- Affected individuals may be homozygous dominant (AA) or heterozygous (Aa).
- Every generation should have affected individuals. They can pass the trait on to their offspring.
- About half of the offspring of an affected individual will inherit the trait.
Autosomal Recessive:
- All affected individuals are homozygous recessive (aa).
- Affected individuals can have unaffected parents (heterozygous carriers).
- About 25% of the offspring of two heterozygous carriers will be affected.
- Unaffected individuals can have affected offspring if they carry a recessive allele.
X-Linked Dominant:
- More females (XX) than males (XY) usually have the trait.
- Affected individuals can be heterozygous (XaXa) or homozygous dominant (XaXa).
- Every affected male will have an affected mother.
X-Linked Recessive:
- More males (XY) than females (XX) usually have the trait.
- Affected individuals are usually hemizygous (XaY).
- Every male offspring of an affected male and unaffected female will be unaffected.
- Females can be carriers (XaXa) or affected (XaXa or XaXa) if both parents carry the recessive allele.
Based on these characteristics, the compatibility of the pedigrees with each type of inheritance can be determined. It is important to carefully analyze the presence or absence of affected individuals in each generation, as well as the patterns of inheritance seen.