May I coin the phrase : Being a tactical extended range diver .

[Belzelbub]

I don't see how the A thing, effects whether or not you can use a breather?

@tursiops post may shed some light on this.

A mutation of this gene results in Brunner syndrome. This gene has also been associated with a variety of other psychiatric disorders, including antisocial behavior.

Especially this part. May also explain the original post as well.