A sub-mutation recognized much later than the Farris sub-mutation. Tigues have a sex-linked mutation -- males are (potential Donor) Gens, while females are channels. Tigue channels have a longer "First Year " than other channels, and thus can disjunct or receive anti-Kill conditioning later than other mutations. Tigues are also more "robust" than the Farris , easily surviving shocks which might be crippling or fatal for a Farris. They also suffer less during Need.
Members of the Tigue family appear in --- Ambrov Keon, Mahogany Trinrose, Zelerod's Doom, and the short story "Donation." http://www.simegen.com/sgfandom/rimonslibrary/donation.html