A couple comes into the clinic for genetic counseling. Both parents are heterozygous for sickle cell trait. What is the chance each of their children will have sickle cell anemia?
50%
25%
75%
100%
The Correct Answer is B
The correct answer is b. 25%.
Choice A: 50%
If both parents are heterozygous for the sickle cell trait (carriers), each child has a 50% chance of inheriting one sickle cell gene from one parent and a normal gene from the other parent. This would make the child a carrier of the sickle cell trait, not someone with sickle cell anemia. Therefore, the chance of having sickle cell anemia is not 50%.
Choice B: 25%
When both parents are carriers of the sickle cell trait (heterozygous), there is a 25% chance that their child will inherit two sickle cell genes (one from each parent), resulting in sickle cell anemia. This is because each parent has one normal hemoglobin gene (A) and one sickle cell gene (S). The possible combinations for their children are AA (normal), AS (carrier), SA (carrier), and SS (sickle cell anemia). The probability of the SS combination is 25%.
Choice C: 75%
A 75% chance is not accurate in this scenario. The 75% figure might be mistakenly considered if one were to add the probabilities of being a carrier (50%) and having sickle cell anemia (25%). However, these probabilities are distinct and should not be combined in this manner.
Choice D: 100%
A 100% chance would imply that every child of the couple would have sickle cell anemia, which is not the case. Since each parent is a carrier, there is only a 25% chance for each child to have sickle cell anemia. The remaining 75% of the time, the child will either be a carrier or have normal hemoglobin.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
Choice A reason:
Weight loss despite increased eating is a classic symptom of type 1 diabetes mellitus in children. This occurs because the body is unable to use glucose for energy due to a lack of insulin. As a result, the body starts breaking down fat and muscle for energy, leading to weight loss even though the child may have an increased appetite.
Choice B Reason:
Pale, moist skin is not typically associated with type 1 diabetes mellitus. This symptom is more commonly related to conditions such as anemia or infections. In type 1 diabetes, the skin may actually appear dry due to dehydration caused by high blood sugar levels.
Choice C Reason:
Weight gain and fluid overload are not characteristic of type 1 diabetes mellitus. In fact, children with type 1 diabetes often experience weight loss. Fluid overload is more commonly seen in conditions such as heart failure or kidney disease.
Choice D Reason:
Poor sleep with frequent awakening is not a specific symptom of type 1 diabetes mellitus. While children with diabetes may experience nocturia (frequent urination at night) due to high blood sugar levels, this is not the primary clinical manifestation. The main symptoms are related to hyperglycemia and the body’s inability to use glucose for energy.
Correct Answer is D
Explanation
Choice A reason:
A 7-year-old child with diabetes insipidus and a urine specific gravity of 1.016 is not in immediate danger. Diabetes insipidus is a condition characterized by excessive thirst and excretion of large amounts of severely diluted urine. A urine specific gravity of 1.016 is within the normal range (1.005 to 1.030). Therefore, this child does not require immediate assessment.
Choice B reason:
A 4-year-old child with asthma and a PCO2 of 37 mm Hg is also not in immediate danger. Asthma is a chronic condition that can cause difficulty breathing, but a PCO2 level of 37 mm Hg is within the normal range (35-45 mm Hg). This indicates that the child’s respiratory status is currently stable, and immediate assessment is not required.
Choice C reason:
A 1-year-old toddler with roseola and a temperature of 39°C (102.2°F) is experiencing a common viral infection that typically causes a high fever followed by a rash. While the fever is high, it is not uncommon for roseola and can be managed with antipyretics and supportive care. This child does not require immediate assessment.
Choice D reason:
A 10-year-old child with sickle cell anemia reporting 8 out of 10 chest pain is in immediate danger and requires urgent assessment. Chest pain in a child with sickle cell anemia can indicate acute chest syndrome, a severe and potentially life-threatening complication. Acute chest syndrome is characterized by chest pain, fever, and respiratory distress, and it requires prompt medical intervention. Therefore, this child should be assessed first.
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