Question

A genetic disease is found in a family that affects the immune system, lungs, heart, and kidneys. A DNA analysis of several affected and unaffected family members determined that the disease is caused by a mutation in a single gene. What type of inheritance pattern is shown in this disease?
A. Incomplete dominance
B. Codominance
C. Pleiotropy
D. Polygenic trait

Answer 1

The described genetic disease affecting multiple systems in the body (immune system, lungs, heart, and kidneys) due to a mutation in a single gene is best characterized by **C. Pleiotropy**.

Pleiotropy refers to a situation where one gene influences multiple phenotypic traits or systems. The other options do not accurately describe the scenario presented:

- **A. Incomplete dominance** and **B. Codominance** refer to how alleles interact and express themselves in traits, not to the effect of a single gene on multiple traits.
- **D. Polygenic trait** refers to traits controlled by multiple genes, which is not the case here since the disease is caused by a mutation in a single gene.

Thus, the correct answer is **C. Pleiotropy**.