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If both parents are carriers for thaless...

If both parents are carriers for thalessemia, which is ai:, autosomal recessive disorder, what are the chan~e~ pregnancy resulting in an affected child?

A

0.25

B

1

C

no chance

D

0.5

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem regarding the chances of having a child affected by thalassemia when both parents are carriers, we can follow these steps: ### Step-by-Step Solution: 1. **Understand the Genetic Condition**: - Thalassemia is an autosomal recessive disorder. This means that a child must inherit two copies of the thalassemia gene (one from each parent) to express the disease. 2. **Identify the Genotypes of the Parents**: - Since both parents are carriers, their genotypes can be represented as Tt, where 'T' is the normal allele and 't' is the thalassemia allele. 3. **Set Up a Punnett Square**: - Create a Punnett square to visualize the genetic combinations that can arise from the cross between the two parents (Tt x Tt). ``` T t ----------------- T | TT | Tt | ----------------- t | Tt | tt | ----------------- ``` 4. **Analyze the Offspring Genotypes**: - From the Punnett square, we can see the possible genotypes of the offspring: - TT (normal) - 1 out of 4 - Tt (carrier) - 2 out of 4 - tt (affected by thalassemia) - 1 out of 4 5. **Calculate the Probability of an Affected Child**: - The probability of having a child affected by thalassemia (tt) is 1 out of 4, or 25%. 6. **Conclusion**: - Therefore, the chances of a pregnancy resulting in an affected child (with thalassemia) when both parents are carriers is **25%**.
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