I doubt that any tuna sold at sushi restaurants east of California have the DNA either.
White Tuna, aka Escolar is not Tuna at all. The fish contains a non-digestible fat. Ever eat a whole bag of Olestra chips, or mistake the chocolate flavored ex lax for brownies? Too much escolar and the exact same effect. Explosive gut decompression syndrome with a real risk of an O-ring blowout.
You should try it (in moderation) because it is delicious, but be warned. A big sashimi plate will prep you for a colonoscopy.