Siblings with thal?

Question:
Theoretically, can it be siblings where one is Thal Major and the other is Thal Intermedia?
Where these two have one or both biological parents.

Yes, even if they have the same set of beta globin genes, because there may be other genetic modifiers at work in the intermedia, such as a coinciding alpha deletion.

I am Intermedia and my sister is minor and I have a sister without Thal. We all have the same parents.

Bobby:

Not to change the subject of discussion, but where do you go for Thal treatment?  Did you initially go to Childrens Hospital in Atlanta?

Just curious............I'm in Arkansas and looking into going to one of the centers, but would like to be closer to home than Oakland or Boston.

Thanks,
Bill

Thank you for your answers, great help for me :-)