Which term describes the mutations responsible for dominant-negative mechanisms?

• A. Adaptive mutations
• B. Functional mutations
• C. Loss-of-function mutations
• D. Gain-of-function mutations

Answer: (C)

The correct term that describes mutations responsible for dominant-negative mechanisms is loss-of-function mutations. Dominant-negative mutations occur when a mutated gene product (such as a protein) antagonizes the activity of the wild-type product. This antagonistic effect typically results from the mutated protein being dysfunctional, meaning that it cannot perform its intended role, which fits the definition of a loss-of-function mutation.

In many cases, the mutated protein can still bind to other proteins or substrates; however, it does not function appropriately, disrupting normal cellular processes. Because this dysfunction occurs despite the presence of the normal gene product, it creates a dominant effect over the wild-type allele.

This understanding is crucial in genetics, particularly in studying diseases where such mutations can lead to significant phenotypic outcomes.