Justicar's Disease (lat. Morbus Justicaris) -- this disease affects only vampires of lower generation (capacity 9 or more), and results in having only inferior Fortitude. These vampires should (or at least clearly have the need to) have superior Fortitude. as their clan adherence would indicate.
Sometimes the disease affects non-Justicars as well, i.e. those vampires with capacity of 9 or above whose in-clan-disciplines would indicate that these vampires should have superior Fortitude. Examples for these vampires are Angus the Unruled, Helena Casimir, Kyle Strathcona, or Enkidu.
With the often sub-optimal appearance and apparent bad health of Nosferatu, it's currently still an open question in the science community if the Nosferatu Justicars also suffer from Justicar's Disease. The indication for this issue is that all three Nosferatu Justicars have inferior Fortitude only.