The rule about treating abbreviations as mathematical applies only to chemical abbreviations. So p. 12 would be treated as a literary abbreviation. DNA(Deoxyribonucleic acid–a molecule) would be capitalized and punctuated mathematically.
The BANA Ad Hoc Chemistry Committee is working on a clarification of this rule.
Sorry, I answered a question that was not asked. If you are transcribing in literary code or Nemeth (not Chemistry Code), DNA would be double-capped and punctuated according to EBAE.