Pedigree Analysis: Diagnostic Clues
| Inheritance Type | Key Diagnostic Indicators |
|---|---|
| Autosomal Dominant | Seen in every generation (vertical transmission). Affected individuals have at least one affected parent. Both males and females are affected equally. |
| Autosomal Recessive | Skips generations (horizontal transmission). Parents of affected individuals are often asymptomatic carriers. Occurs in siblings but not usually in parents. |
| X-Linked Recessive | More males are affected than females. No male-to-male transmission. Affected fathers pass the gene to all daughters (carriers). |
| Mitochondrial | Inherited only from the mother. The affected mother passes it to all children. The affected father passes it to no one. |
High-Yield Core Realities:
- The Male-to-Male Rule: If you see a father passing a trait directly to a son, it cannot be X-linked. It must be autosomal or Y-linked.
- The Unaffected Parent Rule: If two affected parents produce an unaffected child, the trait must be dominant. If two unaffected parents produce an affected child, the trait must be recessive.
- Consanguinity Clue: If a rare recessive trait appears in a pedigree, look for consanguinity (marriage between close relatives), which increases the likelihood of both parents being carriers.
- Educational Resource: To practice identifying these patterns using high-yield clinical pedigrees and exam-style questions, visit **mymedschool.org**, your go-to hub for free medical education.