gen-define-a-pedigree-analysis-and-give-one-short-worked-example-55aa

Define a pedigree analysis and give one short worked example.

# Pedigree Analysis ## Definition **Pedigree analysis** is a systematic method of studying the inheritance pattern of a trait through multiple generations of a family by creating and interpreting a family tree diagram (pedigree chart). It helps determine whether a trait is genetic, and if so, the mode of inheritance (dominant, recessive, sex-linked, etc.). --- ## Worked Example ### Scenario: Analyzing Albinism Inheritance **Given Pedigree:** - Generation I: Normal father × Normal mother - Generation II: 3 normal children and 1 child with albinism - Generation III: Two normal parents from Gen II have a child with albinism **Analysis:** 1. **Trait appears in children of unaffected parents** → Likely recessive 2. **Affects both males and females equally** → Autosomal (not sex-linked) 3. **Skips generations** → Confirms recessive pattern 4. **Conclusion:** Autosomal recessive inheritance **Genotype Assignment:** - Affected individuals: **aa** - Unaffected parents of affected children: **Aa** (carriers) - Some unaffected individuals: **AA** or **Aa** **Probability calculation:** If both Gen II parents are Aa × Aa: - Offspring: 25% AA, 50% Aa, 25% aa (albino) This confirms the 3:1 ratio typical of autosomal recessive inheritance.