TX-008, or 'TX' for short was the first clone successfully produced by Darths Ircune and Quetus before their deaths. A triumph of Sith science, TX layed the foundations for the following clones, allowing Ircune and Quetus to perfect their designs.
However, TX was not what the scientists had expected. Emotionally he was unbalanced and his powers in the Force varied from chaotic to non-existant. Furthermore TX was mute, unable to speak he was forced to communicate through the Force.
Eventually it was decided that TX was more dangerous than anything and the Sith began a man hunt for the young clone.