Porphyria is a group of rare genetic disorders that affect the production of heme, a component of hemoglobin. It can cause a range of symptoms, including abdominal pain, skin sensitivity to sunlight, neurological symptoms, and psychiatric disturbances. While it is not specific to any particular monarch, it has been suggested as a possible explanation for some historical figures' symptoms and behaviors. It's fascinating to learn about the various diseases that have impacted historical figures throughout time!