GED Science TestLife ScienceMedium
A genetic counselor is explaining the inheritance pattern of a rare genetic disorder to a couple. The disorder appears in every generation, affects males and females equally, and an affected parent has a 50% chance of passing the disorder to each child, regardless of the child's sex. This pattern is consistent with which type of inheritance?
- AMitochondrial
- BX-linked recessive
- CAutosomal recessive
- DAutosomal dominant
Show answer & explanationAnswer & explanation
Correct answer: D. Autosomal dominant
Autosomal dominant inheritance is characterized by the trait appearing in every generation, affecting males and females equally, and an affected individual having a 50% chance of passing the allele to each offspring. This matches the described scenario.
Why the other options are wrong
- A. Mitochondrial inheritance is passed only from mother to all children, which does not fit the 'affected males and females equally' and 'affected parent' criteria.
- B. X-linked recessive disorders typically affect males more frequently and often skip generations.
- C. Autosomal recessive disorders often skip generations and require two copies of the affected allele for expression.
Autosomal Dominant Inheritance
A pattern of inheritance where a single copy of an altered gene on a non-sex chromosome (autosome) is sufficient to cause the trait or disease.
- Trait appears in every generation.
- Affected individuals have at least one affected parent.
- Males and females are affected equally.
- Affected parent has 50% chance of transmitting to each child.
Memory trick: Dominant Always Shows, Recessive Really Hides.