AZ, GI, MN,?, YB which one of the following can replace the question mark?

AZ, GT, MN, __ , YB
In this series letter contain AZ, second letter G. From this we can see that A to G increasing order but Z to T decreasing order. 3^rd letter also maintain same pattern respect to 2^nd letter.
Now, we are considering position of each letter according to the alphabetical order.
A + 6 = G, G +6 = M => M + 6 = S
Z - 6 = T, T - 6 = N => N - 6 = H
So, fourth term will be = SH