Final answer:
Gain-of-function mutations are typically dominant and can result in new or enhanced functions of a gene product, while loss-of-function mutations usually cause reduced gene product function and are commonly recessive.
Step-by-step explanation:
Gain-of-function mutations lead to a new or enhanced function of a gene product, and are commonly dominant, resulting in conditions such as oncogene activation. These mutations can be 'dominant negative' when the altered gene product interferes with the wild-type product. Conversely, loss-of-function mutations typically result in a reduced or complete loss of the gene product's function and are usually recessive, as seen with many DNA damage suppressor genes.
While gain-of-function mutations in an essential gene can be dominant negative or lead to dominant lethal inheritance patterns, loss-of-function mutations can result in recessive lethal patterns if individuals are homozygous for the nonfunctional allele. Dominant mutations are typically observed with gain-of-function scenarios, as even a single copy of the mutated gene can lead to a new or altered trait or function that overshadows the normal allele.