Question

If a gene is haploinsufficient, that means that:

A) one functional copy is sufficient to produce a wild type phenotype
B) a loss of function mutation in the gene will likely be dominant over wild type
C) it is expressed at a higher level than normal
D) there is a copy present on each of our 23 chromosomes
E) a mutation has removed one half of the gene

Answer 1

A haploinsufficient gene requires both copies to be functional for a normal phenotype; one functional copy is not enough, making any loss of function mutation likely dominant over the wild type.

Step-by-step explanation:

If a gene is haploinsufficient, it means that having just one functional copy of the gene does not produce enough of the gene's product to result in a normal, or wild type, phenotype. The correct answer to the question is B) a loss of function mutation in the gene will likely be dominant over wild type. This is because, in the case of haploinsufficiency, the one remaining functional gene copy is insufficient to sustain normal function.

In other words, for a haploinsufficient gene, you need both copies of the gene to be functional to have the wild type phenotype. If one copy is mutated, and a loss of function mutation occurs, this is insufficient for normal functioning, resulting in a dominant inheritance pattern of the mutated phenotype. This can have significant implications for inheritance and disease, as individuals with just one mutant copy can exhibit symptoms or characteristics associated with the mutation.