Mutations in the promoter region of the β-globin gene indicate that some areas are more sensitive than others. When mutations occur in consensus sequences (modular elements such as GC box, CAAT box, TATA box), transcription usually increase or decrease?

Decrease.

Explanation:

Consensus sequences may be defined as the most conserved sequences present in the different organisms. They perform similar structure and functions even in the unrelated organisms.

The TATA box, homeo genes and some transcription factors shows the conserved sequences. The mutation in these sequences may disrupt the functions and can cause disease in the organisms as well. The consequences sequences of the transcription factors if mutated decreases the transcription process.

Thus, the correct answer is decrease.