Pedigrees

Jamie Z 2024-11-05

Learning Goals

1. Understand the structure and function of pedigree diagrams
2. Interpret a pedigree diagram to predict the genotypes of individuals
3. Infer from a pedigree diagram whether a gene trait is dominant or recessive
4. Infer from a pedigree diagram whether a gene for a trait is autosomal or sex linked

Pedigree

A chart that shows the inheritance of a trait over several generations

Reading a Pedigree

Types of Pedigrees

Autosomal Dominant

• Cannot be recessive as two affected parents could not have unaffected offspring
• Parents must be heterozygous

Autosomal Recessive

• Cannot be dominant as two unaffected parents could not have an affected offspring
• Parents must be heterozygous

X-linked Dominant

• Sex linkage cannot be confirmed
• 100% incidence of affected daughters suggest X-Linked dominance

X-linked Recessive

• Sex linkage cannot be confirmed
• 100% incidence of affected sons suggest X-linked recessive

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