Answer: porphyria

AnswerCrossword Clue
porphyriaA rare hereditary disease in which the blood pigment hemoglobin is abnormally metabolized. Porphyrins are excreted in the urine, which becomes dark; other symptoms include mental disturbances and extreme sensitivity of the skin to light
porphyriaany of various disorders of metabolism resulting in the excretion of an excessive quantity of porphyrins in the urine