Question

A number of different types of mutations in the HBB gene can cause human ?-thalassemia, a disease characterized by various levels of anemia. Many of these mutations occur within introns or in upstream noncoding sequences. Explain why mutations in these regions often lead to severe disease, although they may not directly alter the coding regions of the gene.

Select the three correct answers

	a.	mutations in upstream sequences may cause frameshift and disrupt protein production
	b.	introns may become exons by means of alternative splicing
	c.	mutations in introns may upset the fidelity of proofreading system
	d.	mutations in introns may affect mRNA stability or translation
	e.	mutations in introns may affect RNA splicing
	f.	mutations in upstream sequences may disrupt transcription factor and/or polymerase binding

Answer 1

A number of different types of mutations in the HBB gene can cause human ?-thalassemia, a disease characterized by various levels of anemia.

Many of these mutations occur within introns or in upstream noncoding sequences. mutations in these regions often lead to severe disease, although they may not directly alter the coding regions of the gene. because Mutations in introns may affect RNA splicing.

Mutations in upstream sequences may disrupt transcription factor and/or polymerase binding