Determining Genotypes in Dominant Pedigrees
This page focuses on how to analyze autosomal dominant pedigree charts to determine individual genotypes, which is crucial for pedigree analysis examples.
Key points for analyzing dominant pedigrees:
- Shaded shapes (affected individuals) can be either homozygous dominant (AA) or heterozygous (Aa)
- Unshaded shapes (unaffected individuals) are always homozygous recessive (aa)
- Genotypes of some individuals may remain unknown due to limited information
Example: In a dominant pedigree, if an affected parent (Aa) has a child with an unaffected parent (aa), the child has a 50% chance of being affected (Aa) and a 50% chance of being unaffected (aa).
The page provides a detailed example of a dominant pedigree, demonstrating how to deduce genotypes based on parental information and offspring phenotypes.
Highlight: In dominant pedigrees, heterozygous individuals (Aa) are still considered affected because the dominant allele is expressed in their phenotype.
The page also includes a Punnett square to illustrate the possible genotype combinations when a heterozygous individual (Aa) mates with a homozygous recessive individual (aa).
Vocabulary: Heterozygous refers to having two different alleles for a particular gene, while homozygous means having two identical alleles.