Dependent Dropdown based on cell value from formula

[jordiejones]

I have a formula in A2 that reads the age of a person based on the date entered in A1. Then A3 returns a letter based on age group: L,J,A,G. These are the category headings for 4x dynamic lists that contain MD names that work with that specific age group. I’ve found countless indirect formulas and dependent drop down lists but can’t find any based on the returning a list from the contents of a cell.
I’ve got a range with label heading that are in a named range (AgeGroup) the values below each group represent the MDs for each category. Any help would be greatly appreciated! Thanks in advance!

 

[Toadstool]

I'm having difficulty interpreting the requirement. Could you copy&paste an example of your data and which list is dependent on which cell?