GED Science TestLife ScienceHard
A genetic counselor is explaining the inheritance pattern of a rare genetic disorder to a couple. The disorder appears in every generation, affects both males and females equally, and an affected parent has a 50% chance of passing the disorder to each child. What type of inheritance pattern is being described?
- AAutosomal Recessive
- BMitochondrial Inheritance
- CX-linked Recessive
- DAutosomal Dominant
Show answer & explanationAnswer & explanation
Correct answer: D. Autosomal Dominant
Autosomal dominant inheritance is characterized by the disorder appearing in every generation (no skipping), affecting males and females equally (autosomal), and an affected individual having a 50% chance of passing it to their offspring (dominant).
Why the other options are wrong
- A. Autosomal recessive disorders often skip generations and require two copies of the affected gene.
- B. Mitochondrial inheritance is passed only from mother to all offspring, and affects both sexes, but doesn't have the 50% transmission risk from an affected parent in the same way.
- C. X-linked recessive disorders typically affect males more severely and show a different inheritance pattern through females.
Autosomal Dominant Inheritance
Autosomal dominant inheritance is a pattern of inheritance where a single copy of an altered gene on a non-sex chromosome (autosome) is sufficient to cause a genetic disorder. It affects males and females equally and typically appears in every generation.
- Affected individuals usually have an affected parent.
- Occurs in every generation; does not skip generations.
- Males and females are affected equally.
- Affected person has a 50% chance of passing the trait to each child.
Memory trick: Dominant Dads Don't Skip Generations, 50% for Sons & Daughters!