The main ones are cytosine , guanine , adenine -LRB- DNA and MISC@1 -RRB- , thymine -LRB- MISC@2 -RRB- and uracil -LRB- MISC@1 -RRB- , abbreviated as C , G , A , T , and U , respectively .

These are abbreviated as C , G , A , T , U , X and HX respectively .
