Meet Brenden Adams, a 12-year-old boy who already is 7 feet tall (2.1 m) and couldn't stop growing:
And though friends say Brenden is just a regular kid, he's obviously not like anybody else. He has to duck through most doorways and sit sideways at his school desk because his knees don't fit under it.
In his mom's sport utility vehicle, he has to fold down the second row of seats, sit in the third row and stretch his legs out over the middle row in order to sit comfortably. His shoe size? 18 and still growing.
The cause? Doctors think that it's a chromosomal abnormality:
For years, doctors continued to search for the source and an answer to Brenden's unstoppable growth. He went through multiple tests and X-rays as medical experts tried to determine what was going on inside Brenden's body.
Then, finally, a breakthrough -- when Brenden was eight years old and already the size of an adult.
"I have to say that the hematologists and oncologists here actually helped us figure it out," admits Parisi. "He has a very unusual rearrangement of his genetic material. It's what's called an inversion of chromosome-12 and it affects every single cell in his body."