Which statement about Sickle Cell Anemia is not accurate (is false) ?

Question

BlackTom AI · Accepted Answer

Sickle cell anemia is an autosomal recessive disorder caused by a single base substitution in the beta-globin (HBB) gene on chromosome 11, not an X-linked condition.

1. Relevant knowledge points and concepts
- Inheritance pattern: Sickle cell disease (classically HbSS) is autosomal recessive; both males and females can be equally affected. Heterozygotes (HbAS) have sickle cell trait.
- Molecular cause: A point mutation in codon 6 of the beta-globin gene (GAG → GTG) replaces glutamic acid with valine (Glu6Val).
- Pathophysiology: The valine substitution produces a hydrophobic patch that promotes polymerization of deoxygenated hemoglobin S, deforming red blood cells into a sickle shape, causing vaso-occlusion and hemolysis.

2. Step-by-step reasoning checking each option
- A) "A homozygous recessive condition" — correct: classic sickle cell disease requires two sickle alleles (HbSS), so this statement is true.
- B) "Almost exclusively affects males because it is an X-linked disorder" — false: the HBB gene is on autosome 11, so the disease is not X-linked and does not predominantly affect males. Both sexes are equally at risk when homozygous for the mutation.
- C) "Results from a single base mutation in the allele that codes for Hemoglobin" — correct: the disease arises from a single nucleotide substitution causing an amino acid change in β-globin.
- D) "Once the cells change shape (sickle), blood vessels can be blocked" — correct: sickled erythrocytes are rigid and can cause vaso-occlusive crises by blocking microvasculature.
- E) "All of these are false" — incorrect because A, C, and D are true; not all statements are false.

3. Intermediate molecular detail
- Mutation: DNA codon GAG → GTG in HBB; mRNA codon GAG → GUG; amino acid change Glu → Val at position 6.
- Consequence: Hemoglobin S polymerizes under low O2, causing RBC sickling and clinical complications.

4. Why the correct answer is correct
Option B is the only statement that contradicts established genetic and molecular facts: sickle cell is autosomal recessive (chromosome 11), not X-linked, so it does not almost exclusively affect males.

5. Why other options are incorrect/true
A, C, and D are true statements as explained; E is false because not all listed statements are false.

Conclusion: The false statement is B) Almost exclusively affects males because it is an X-linked disorder, which matches the provided answer.

Which statement about Sickle Cell Anemia is not accurate (is false) ?单项选择题

类似问题

Human ABO blood types are an example of which type of inheritance?

A farmer notices a wheat plant in their field that is significantly more resistant to drought than the surrounding plants. In which scenario would this drought-resistant trait be most likely to be passed on to future generations of wheat?

A parent's genotype influences their child's:

Which is the genotype of a girl who has hemophlia and sickled cell anemia A) XhXhss B) XhXHsS C) XHXHss D) XHXHSS

You own a bond that pays $64 in interest annually. The face value is $1,000 and the current market price is $1,021.61. The bond matures in 11 years. What is the yield to maturity?

更多留学生实用工具

智能学习助手

风格化写作助手

论文查重助手

文献引用助手

课堂转译助手

课堂笔记助手

Quiz搜索助手

学校历年真题

智能刷题助手

智能匹配练习

希望你的学习变得更简单