In one form of b-thalassemia, patients have significantly reduced levels of b-globin transcripts. Notably these b-globin transcripts are less than half the length of the normal b-globin mRNA. These patients exhibit elevated levels of HbF and no detectable HbA₁. Which of the following best explains the molecular reason for these observations? A) addition of 7-methylguanosine to the b-globin mRNA B) covalent modification of the b-globin protein C) improper folding of the b-globin protein D) promoter mutations in the b-globin gene E) splicing alteration of the b-globin mRNA

Question

Quizplus · Accepted Answer

The Answer is E
EXPLANATION: Numerous b-thalassemias result from mutations in the sequences that control proper splicing of the b-globin transcript. These mutations lead to b-globin mRNAs that are shorter or longer than the normal b-globin mRNA. Although mutations in the promoter region of the b-globin gene will lead to reduced levels of expression and thus, to reduced levels of b-globin mRNA, they generally do not result in mRNAs that are shorter than normal.

In One Form of B-Thalassemia, Patients Have Significantly Reduced Levels