Barclay's Protomorphosis Syndrome

Barclay Protomorphosis Syndrome was a genetic regression disease that affected the crew of the USS Enterprise-D.

The disease caused the crew to revert back to more primitive lifeforms while Captain Jean-Luc Picard and Lieutenant Commander Data were off ship. When Picard and Data returned they ship adrift and, at first glance, deserted. Upon closer investigation they discovered that members of the crew had de-evolved, including Deanna Troi who had become a frog-like creature and Commander William T. Riker who had reverted to a neanderthol.

Data and Picard, who was himself beginning to be affected by the disease, soon found a cure and restored the Enterprise crew to normal.

The disease was named by Dr. Beverly Crusher after the first known patient of the disease, Lieutenant Reginald Barclay.