Cygnokemia

Cygnokemia was an extremely rare terminal disease that affected Humans. It had no known cure.

Doctor Joseph M'Benga's daughter Rukiya was diagnosed with cygnokemia in 2258 and given a prognosis of twelve weeks. With there being no known treatment, he decided to secretly suspend her within the pattern buffer of the medical transporter on the USS Enterprise, thereby arresting the course of the disease while he searched for a cure. (SNW: "Ghosts of Illyria")

He later asked Elder Gamal if the Majalans could share information for a cure. His request was declined because of existing policy preventing the sharing of technology, even with respect to medical intervention. However, he later helped M'Benga to develop a treatment for cygnokemia, although Gamal warned that it would not be a cure. The doctor hoped that it would be the first step to one. (SNW: "Lift Us Where Suffering Cannot Reach")

His search for the cure was ended with no result when the Enterprise and all but him, Hemmer, and Rukiya were affected by a lifeform inhabiting a nebula that presented M'Benga with the choice of parting with his daughter, as it was within the lifeform's power remove the disease by having her join with it indefinitely. (SNW: "The Elysian Kingdom")