i believe they have a skin disease called Porphyria Cutanea Tarda

The erythropoietic porphyrias and porphyria cutanea tarda are considered to be chronic conditions.

The first line of defense is avoidance of factors, especially alcohol, that could bring about symptoms.

Congenital erythropoietic porphyria (step 4); porphyria cutanea tarda (step 5); hepatoerythopoietic porphyria (step 5); erythropoietic protoporphyria (step 8).

All of the hepatic porphyrias--except porphyria cutanea tarda--follow a pattern of acute attacks separated by periods during which no symptoms are present.