My son has been diagnosed with Cystic Fibrosis. I am not looking for medical advice regarding his condition, but I am very interested in understanding the genetic causes of his condition.
In addition to the common CF mutation Delta F508, my son's genetic testing revealed both 6T and 9T variants of the PolyT sequence.
If I understand it correctly, it seems that the variants (I have found repeated reference to 5T, 7T, and 9T variants, but almost nothing on 6T) are tied to errors in the RNA transcription of the CFTR protein, but I don't understand how, or what the difference between these variants are.
What does "variant of the PolyT sequence" mean in this context, what are the difference between 5T, 6T, 7T, and 9T, and how do they impact the production of the CFTR protein?