Question

With regard to the estimation and interpretation of the recurrence of risks for genetic disorders, nurses should be aware that:

1) With a dominant disorder, the likelihood of the second child also having the condition is 100
2) An autosomal recessive disease carries a one in eight risk of the second child also having the disorder.
3) Disorders involving maternal ingestion of drugs carry a one in four chance of being repeated in the second child.
4) The risk factor remains the same no matter how many affected children are already in the family.

Answer 1

For autosomal dominant disorders, a child has a 50% chance of inheritance. For autosomal recessive disorders, there is a 25% chance the child will have the disorder, a 50% chance of being a carrier, and a 25% chance of being unaffected for each pregnancy. The risk for X-linked recessive disorders depends on the sex of the child and the carrier status of the mother.

Step-by-step explanation:

Recurrence Risks for Genetic Disorders

When considering the recurrence of risks for genetic disorders, it's important to understand different patterns of inheritance. For autosomal dominant disorders, if one parent is heterozygous (Nn) and the other parent has two normal alleles (nn), each child has a 50% chance of inheriting the disorder.

Conversely, for autosomal recessive disorders, when two carriers have children, the offspring have a 1 in 4 chance (or 25%) of being affected by the disorder, a 2 in 4 chance (or 50%) of being carriers, and a 1 in 4 chance of being unaffected.

This is because the inheritance pattern of an autosomal recessive disorder with two carrier parents reflects a 3:1 probability of expressions among offspring.

Regarding X-linked recessive disorders, a son born to a carrier mother has a 50% chance of being affected, while a daughter has a 50% chance of being a carrier. It's also important to note that the risk factor for genetic disorders remains the same no matter how many affected children are already in the family.