What type of mutation alters a gene product to confer a new or abnormal function?

• A. Gain-of-function mutation
• B. Recessive mutation
• C. Silent mutation
• D. Loss-of-function mutation

Answer: (A)

A gain-of-function mutation is one that results in a gene product with a new or enhanced activity compared to the normal function of that gene. Such mutations can lead to the protein being more active, acquiring new functions, or being expressed in a different cellular context than it normally would be. This contrasts with other types of mutations.

Recessive mutations typically lose function or do not produce any effect in the presence of a dominant allele, meaning they do not convey new functions. Silent mutations change a nucleotide in the DNA sequence but do not change the amino acid sequence of the protein, resulting in no alteration of protein function. Loss-of-function mutations, as the name suggests, result in a gene product that is inactive or has a reduced level of activity, impairing or eliminating its normal functionality. Therefore, a gain-of-function mutation is distinct in its ability to provide new or enhanced functionalities to the gene product.