Autosomal dominant inheritance vs Autosomal recessive inheritance
How to tell Autosomal dominant inheritance and Autosomal recessive inheritance apart when a board question makes them look alike.
Autosomal dominant is vertical and one allele; autosomal recessive is sibling clustering from carrier parents and two alleles.
Side by side
Autosomal dominant inheritance often shows vertical transmission, affected individuals in each generation, male-to-male transmission possible, and disease with one mutant allele.
Autosomal recessive inheritance often shows affected siblings with unaffected carrier parents, consanguinity, skipped generations, and equal sex distribution.
One pathogenic allele is sufficient through haploinsufficiency, dominant negative effect, or gain of function.
Both alleles must be affected, often causing enzyme loss-of-function disease with carriers remaining clinically unaffected.
Affected parent to affected child, male-to-male transmission, and 50 percent recurrence risk support autosomal dominant inheritance.
Unaffected parents with affected child and 25 percent recurrence risk support autosomal recessive inheritance.
The trap
Equal male/female involvement occurs in both; generation pattern and parent phenotype separate them.
The repair move
For autosomal pedigrees, use vertical versus sibling-only pattern before memorizing disease examples.
Try a free question
CoreA 28-year-old man with a family history of Huntington disease has a father, paternal aunt, and paternal grandfather all affected. Both sexes are affected equally across three generations. Each affected parent has approximately 50% of children affected. Which pattern of inheritance is most likely?
Show answer and explanation
Answer: A. Autosomal dominant. Autosomal dominant inheritance shows vertical transmission across generations, both sexes affected equally, male-to-male transmission possible, and approximately 50% recurrence risk from each affected parent. Huntington disease, Marfan, NF1, polycystic kidney disease (adult) are classic AD examples.
Why the other choices are tempting
- B. Autosomal recessive shows affected siblings of UNAFFECTED carrier parents, not vertical transmission across three generations.
- C. X-linked recessive predominantly affects males through carrier mothers and forbids father-to-son transmission.
- D. X-linked dominant forbids father-to-son transmission.
- E. Mitochondrial inheritance forbids paternal transmission entirely.
Flashcards
Tap a card to flip it.
What clue supports Autosomal dominant inheritance?
Choose Autosomal dominant inheritance when the stem gives this pattern: Autosomal dominant inheritance often shows vertical transmission, affected individuals in each generation, male-to-male transmission possible, and disease with one mutant allele.
What clue supports Autosomal recessive inheritance?
Choose Autosomal recessive inheritance when the stem gives this contrasting pattern: Autosomal recessive inheritance often shows affected siblings with unaffected carrier parents, consanguinity, skipped generations, and equal sex distribution.
Quick answers
What is the fastest way to tell Autosomal dominant inheritance from Autosomal recessive inheritance?
Autosomal dominant is vertical and one allele; autosomal recessive is sibling clustering from carrier parents and two alleles.
What is the key clue for Autosomal dominant inheritance?
Autosomal dominant inheritance often shows vertical transmission, affected individuals in each generation, male-to-male transmission possible, and disease with one mutant allele.
What is the key clue for Autosomal recessive inheritance?
Autosomal recessive inheritance often shows affected siblings with unaffected carrier parents, consanguinity, skipped generations, and equal sex distribution.
What is the common trap with Autosomal dominant inheritance vs Autosomal recessive inheritance?
Equal male/female involvement occurs in both; generation pattern and parent phenotype separate them.