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 determines that the disease is caused by a mutation in a single gene. What type of inheritance pattern is shown in this disease?

Question

A: codominance

B: pleiotropy

C: polygenic trait

D: incomplete dominance

Answer 1

The correct answer is B: pleiotropy.

Pleiotropy refers to a situation where a single gene affects multiple traits or systems in the organism. In this case, the mutation in a single gene is affecting the immune system, lungs, heart, and kidneys, which illustrates the concept of pleiotropy.

The other options are not appropriate:

• A: Codominance refers to a condition where both alleles in a heterozygote are fully expressed (like in blood types).
• C: Polygenic traits involve multiple genes contributing to a single trait, which does not apply here since we are dealing with a single gene mutation.
• D: Incomplete dominance is when the phenotype of the heterozygote is intermediate between the phenotypes of the homozygotes.

Thus, pleiotropy is the best answer.