Abstract
DNA-based data storage systems have evolved as a solution to accommodate data explosion. In this letter, some properties of DNA codewords that are essential for an archival DNA storage are considered for the design of codes. Constraint-based DNA codes, which avoid runs of nucleotides, have fixed GC-weight, and a specific minimum distance is presented. An altruistic algorithm that enumerates DNA codewords with the above constraints is provided. A theoretical bound on such DNA codewords is obtained. This bound is tight when there is no minimum distance constraint.