Extract:
Sickle-Cell Anemia
Healthy red blood cells are shaped like a disc. Each cell contains the protein hemoglobin, which carries oxygen throughout the body. In some people, a crescent shaped cell forms instead of the normal discshaped cell. The crescent-shaped cells contain abnormal hemoglobin. These sickle-shaped cells are fragile and are unable to carry oxygen properly throughout the body.
Sickle-cell anemia is an inherited disease that affects about 72,000 people in the United States. It is more common among people of South American or African descent. The genes for sickle-cell anemia are inherited from both parents. When both parents carry a gene for the trait for sickle-cell, there is a one in four chance that they will pass the disease on to their children.
Symptoms of sickle-cell anemia can include sudden occurrences of extreme abdominal and back pain, bone pain, fever, fatigue, and a rapid heart rate. One patient compared the pain in his back to a jackhammer and said the pain could take over his entire body. Another patient, an eight-year-old girl, described fevers and the feeling of someone squeezing her arms and legs.
Cycles of symptoms are often unpredictable and can occur infrequently or almost constantly. Some people who are affected report weekly occurrences of persistent pain, while others report occurrences once a month. Some report that relief comes only by using powerful painkillers. For others, relief comes with bed rest and a hot-water bottle. Most agree that while the challenges of managing sickle-cell anemia are great, with diligent care, it can be managed.
Which of the following is not listed as a detail in the passage?
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A
People of African descent may be prone to sickle-cell anemia.
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B
Symptoms of sickle-cell anemia may include abdominal pain.
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C
The red blood cells of sickle-cell patients are unusually shaped.
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D
Vitamin and mineral deficiencies may result in some anemia.
The detail not listed is that vitamin and mineral deficiencies may result in some anemia, as the passage attributes sickle-cell anemia exclusively to genetic inheritance without mentioning nutritional causes.
A) People of African descent may be prone to sickle-cell anemia
This is explicitly stated: the disease "is more common among people of South American or African descent," establishing ethnic prevalence.
B) Symptoms of sickle-cell anemia may include abdominal pain
This is explicitly stated: symptoms include "sudden occurrences of extreme abdominal and back pain," listing abdominal pain among primary manifestations.
C) The red blood cells of sickle-cell patients are unusually shaped
This is explicitly stated: instead of normal "disc-shaped" cells, patients have "crescent-shaped" or "sickle-shaped" cells containing abnormal hemoglobin.
D) Vitamin and mineral deficiencies may result in some anemia
This never appears. The passage attributes sickle-cell anemia entirely to genetic inheritance ("inherited disease," "genes... inherited from both parents") with no reference to nutritional deficiencies causing any form of anemia.
Conclusion
Three details appear explicitly in the text: ethnic prevalence patterns, specific symptom manifestations, and abnormal cell morphology. The nutritional deficiency claim represents external medical knowledge absent from this passage's focused discussion of sickle-cell anemia's genetic basis.