In either Nemeth or Chemistry code, the letters in a DNA sequence are individually capitalized since each letter stands for a specific nucleotide.
[braille],A,T,A,A,C,A,C,G
Regarding "DNA" in Nemeth code we follow EBAE for abbreviations so it would be double-capped. In Chemistry code we individually capitalize letters if the abbreviation is chemical, which this is (deoxyribonucleic acid).