Anton's Key was a genetic modification that afflicted Julian 'Bean' Delphiki and four of his nine children, discovered and named by Anton. One who had this condition was said to have Anton's Key "turned”.
The modification caused gigantism, extremely high intelligence and a virtually unlimited capacity for learning. Both were caused by a slow, but constant and unstoppable growth from birth of both body and, more remarkably, brain. Children with Anton's Key turned were born prematurely, and, despite low birth weight and shorter gestation period, did not require any extra attention as most premature babies do. All of the normal human growth milestones were accelerated, including, but not limited to, toilet training, walking, and talking. However, they still reached puberty at the normal human age, and had no growth spurts.
As the child grew, the immense size of the body caused circulation difficulties for the heart. The heart would be forced to pump blood through a network of arteries and veins much larger than the average human's network. In the process, the subject would eventually experience congestive heart failure, causing death. As a result, persons in whom Anton's Key has been turned typically did not live past their twentieth birthday.
Eventually, a cure for the gigantism symptom was discovered by the son of Bean, Ender Delphiki, through adding organelles to the body. However, it was possible that the original Anton's Key was still around if Arkanian Delphiki reproduced before his death.