Accepting Input regardless of Case

Hi I am trying to get my script to accept input regardless if the person enters a or A. here is the portion of the code where I get the input.

echo -n 'Please enter your choice:'     # prompt user for input.
 read reply                  # read input
 echo
 case $reply in              # process input
   "a")
     echo "Add Submenu:"
     ./add.sh                # Takes you to the add script
     ;;

right now it only accepts "a" as the input, how can I get it to accept either "a" or "A"?

a|A)

Regards,
Alister

Or: [aA])