Is the mutation in the gene in the TATAAA box or the promoter and why?

Answer 1

Without knowing more detail, this question is hard to answer specifically. That being said, we can still make some general observations about TATA boxes and promoters that might answer your question.

Promoters are a region of non-coding DNA upstream of genes. Each gene has a promoter region. This region is a crucial location for the binding of transcription factors and RNA polymerase that create RNA from the gene's DNA.

The TATA box is a specific region of the promoter that contains a series of repeating Thymine and Adenine DNA bases. It acts as a sort of 'homing-beacon' for the transcription initiation factors to bind to and initiate gene transcription.

As you can imagine, if a mutation were located in the TATA box, transcription would have a near-impossible time locating the region and binding to it. This would result in that gene hardly ever being transcribed and translated to make its protein. A lack of a particular protein can interrupt many important cellular processes and lead to diseases such as Huntington's, gastric cancer, blindness, HIV-1, and many other diseases.

There are other non-coding DNA bases in the promoter besides the TATA box, so a mutation in these regions would be far more likely. Some non-coding sequences do serve purposes for things that researchers are still discovering on a consistent basis, such as epigenetics and cell regulation. However, the vast majority has no known function. Even still, a location in the promoter outside the TATA box is likely to be vastly less impactful than one inside of the TATA box would be.