How the hell would you know they had it:

Being extremely startled by an unexpected noise or sight is the main characteristic of the disorder with the peculiar name of Jumping Frenchmen of Maine.

It's not just bolting when someone sneaks up behind you, explains Butcher. Patients with the disorder flail their arms, cry out and repeat words. First identified in some of Maine's lumberjacks of French-Canadian origin, the odd reflex has been identified in other parts of the world, too.

Exactly as they looked when weasling out of the Iraq War.