Question

If the recessive autosomal mutation is rare, most matings of heterozygous carriers will be with someone who _________ the mutant gene?

1) carries
2) does not carry
3) inherits
4) does not inherit

Answer 1

In the context of a rare autosomal recessive mutation, most matings involving heterozygous carriers will likely be with individuals who do not carry the mutant gene, due to its low prevalence.

Step-by-step explanation:

When considering autosomal recessive mutations which are rare, it's important to understand the genetic principles governing inheritance. Carriers of a recessive mutation, who are heterozygous for this mutation, do not express the disorder's symptoms due to the presence of one normal allele. However, they can pass the mutation on to their offspring. If such a carrier mates with an individual who does not have the mutant gene (is homozygous for the normal allele), the likelihood of their offspring inheriting the disorder depends on the genotype of the other parent.

In a mating between a heterozygous carrier and a non-carrier, the outcomes are: 50% chance for another heterozygous carrier (asymptomatic) and a 50% chance for a homozygous non-carrier. Importantly, there is 0% chance for homozygous recessive offspring which would present the disorder if the other parent is not a carrier. This brings us to understand that in the context of a rare autosomal recessive mutation, most heterozygous carriers will likely mate with someone who does not carry the mutant gene due to its rarity in the population.