Question

In disorders with autosomal recessive inheritance, the affected children have received a disease-causing mutation from both parents. In the family shown in the pedigree, we can conclude that the parents are both healthy, heterozygous carriers of the mutation. What is the risk that their second child will develop the disease just as their first daughter? a) 0% risk b) 25% risk c) 50% risk d) 100% risk

Answer 1

In autosomal recessive disorders, each child born to parents who are carriers of the disease has a 25% chance of developing the disease. This is because they have to inherit the disease-causing allele from both parents, each having a 50% chance of passing it on. This risk is the same for every child these parents have.

Step-by-step explanation:

In disorders with autosomal recessive inheritance, a child can only develop the disease if they inherit a disease-causing mutation from both parents. However, parents who are carriers of the disease may not show symptoms themselves. The probability that a child will receive both disease-causing alleles, one from each parent, is 25%. This is because each parent has a 50% chance of passing on the disease-causing allele to each of their children. Therefore, the child has a 50% chance of inheriting the allele from the mother, a 50% chance of inheriting it from the father, and the multiplication of these probabilities results in a 25% chance that the child will inherit the allele from both parents and thus develop the disease. This risk remains the same for every child the couple has, as the passing of alleles is independent of previous events.

Learn more about Autosomal Recessive Inheritance