You're exhausted -- so tired that you could collapse. In fact, your helpless carcass was hauled by ambulance to an emergency room where a sneering doctor called you a sissy. Maybe your potassium was a bit low and you were advised to drink more tomato juice. You were kicked out with a fat bill -- until the same thing happens next week, and then again a month later.

What that doctor didn't know is that you were unlucky enough to be born with the CACNA1S and SCN4A mutations that cause a seldom-diagnosed syndrome called "Periodic Paralysis." Faulty potassium pumps are letting the energy leak out of your muscle fibers, leaving you as limp as a shed of angel-hair pasta. With symptoms starting in adolescence, you've been suffering attacks of weakness brought about by a heavy carbohydrate meal, a swig of alcohol, a dose of the wrong medication, or even a sudden chill in the weather.

Don't expect any sympathy from friends or medical professionals. They can see you're perfectly healthy and will assume that you're just a knucklehead psychiatric patient faking symptoms to avoid a court appearance. Their attitude might change if your attack gets serious enough to interfere with your breathing or cause a skipping heartbeat or EKG changes, but most patients recover within a hour, and doctors will end up blaming the symptoms on fatigue, or maybe low blood sugar.

You can settle the question by getting expensive genetic testing to prove you have the mutation, assuming you have ready cash and access to one of the handful of institutions capable of performing such tests.

Or you could talk to Mom and Dad. Since many forms of Periodic Paralysis are passed along as an autosomal dominant genes, at least one your your parents has probably been getting "dissed" for attacks of noodle-like floppiness since the days before your were born. Maybe now at last they'll finally earn your grudging respect for their long-overlooked disability!