In that case, I would probably first create the square "matrix" with all entries initialized to 0. Then I would read in the data you have as in my previous reply. Finally, I would loop over the entries making them symmetric. To do this, you could make an array @A with entries AA,...,ZH and then do the symmetrizing over the matrix entries $M{$A[i]}{$A[j]} where i<j.
AA,...,ZH includes 208 values, doesn't it? So it seems like your matrix is much bigger than 39 by 39. But I may be misunderstanding something still.
It is probably possible to do all this in fewer steps, but there probably isn't much change in efficiency.
(I am getting disconnected a lot, so I may stop posting till later.)
chas