A BLUE MAN, SLEEP EATERS AND A YOUNG BOY WHO STANDS OVER SEVEN FEET TALL, ON "PRIMETIME: MEDICAL MYSTERIES," AUGUST 19 ON ABC

Whether examining how one man's skin turned blue or how a 12-year-old boy could already be seven feet tall, "Primetime: Medical Mysteries" reports on some of the strangest conditions known to medicine. The "Primetime" limited series examines cases that leave scientists and doctors with unanswered questions when trying to explain the human body. "Primetime: Medical Mysteries" airs TUESDAY, AUGUST 19 (10:00-11:00 p.m., ET) on the ABC Television Network.

John Qui�ones reports on a 12-year-old boy who can't stop growing. Brendan Adams' unusual size affects every part of his life -- the desk he's outgrown in his sixth grade classroom, even the way he has to fold down the middle seat in his mother's SUV just to fit in the vehicle. While some of the tallest people in history have struggled with exceptional height, their conditions have a more common cause -- hormones -- but doctors say Brendan's situation is the only one of its kind. It wasn't until he was eight years old, after years of searching for answers, that his blood work showed the chromosome inversion that affects every cell in his body. Can anything be done to stop his growth? His doctor, Gad Kletter, proposes an idea that may seem a little crazy but could work.

Also: Paul Karason was a fair-skinned man with reddish-blonde hair before his transformation. Now his skin is blue. Juju Chang reports on a rare and permanent medical syndrome know as Argyria, silver poisoning. It is caused from colloidal silver, a home brew of microscopic silver particles suspended in water. Despite an FDA assertion there's no medical reason to take the colloidal silver, many people like Paul take it with hopes of rejuvenation and better health. A second argyria patient got it from nose drops prescribed by her doctor when she was a child. Chang follows their journey to find out what's it like to be "blue."

And: Deborah Roberts reports on people who have a medical condition called SRED, Sleep Related Eating Disorder, where they eat in their sleep. Sometime it's once, sometimes many times a night, fast asleep; the sufferers eat things as odd as cat food, coffee grounds, eggshells or soap, and don't even know they're doing it. Doctors are fairly certain that genetics, not hunger, play a role in this condition. "Primetime" captures the nocturnal journeys of two women afflicted with SRED. Viewers get a first hand understanding of its consequences, which can include weight gain and exhaustion. Dr. Carlos Schenck, a leading researcher in the field of sleep medicine, explains that "it's not will power. It's not a psychological problem. It's a major physiological force coming from within your brain and body to eat at night so inappropriately."

Then: "Primetime" examines a strange and isolating condition that comes and goes, in which a patient suddenly can't speak in anything but a squeak. Spasmodic Dysphonia, also known as "strangled voice," is a neurological condition that affects an estimated 30,000 Americans. One of them is the cartoonist who draws the internationally famous cartoon strip, "Dilbert." Doctors believe "strangled voice" is caused when a part of the brain misfires. Surprisingly, the treatment is a Botox shot to the throat. David Muir reports.

The hour will also feature a medical mystery, designed for viewer participation. This segment, called "You Be the Doctor," allows viewers to assess medical clues and vote online or by text messaging their diagnosis as the show progresses. What's really wrong with a toddler on the brink of death? His twin is fine, but why is he burning with fever in the pediatric ICU?

Ann Reynolds and Terry Wrong are the senior producers of "Primetime: Medical Mysteries." Rudy Bednar is the executive producer.