Dax, son of Kang, Kang's firstborn, was the namesake and godson of Curzon Dax, born some time in the late 2280s. Curzon felt it an incredible honor to be nominated as the godfather of a Klingon child, at a time when relations between the Klingon Empire and the Federation were still quite hostile.
The young boy Dax was murdered by the Albino a few years after 2290, when his father defeated the Albino's forces in a devastating raid. For his defeat, the Albino enacted revenge upon Kang by infecting his son with a slow-acting genetic virus. Kang and Curzon, along with Kor and Koloth (whose sons had also been murdered by the Albino) together swore a blood oath to avenge these deaths.