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Because iron metabolism and incorporation into hemoglobin occurs inside the mitochondria , Bcl-xL was suggested to play additional roles in regulating this process in erythrocytes which could lead to a role in polycythemia vera , a disease where there is an overproduction of erythrocytes .
 polycythemia vera
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: media, plant, vehicle, astronomical object, time, disease, animal, location, person, organization, mythical figure, food, biology, geographical phenomenon, instrument, event 
Text: {0} 
Answer:
 polycythemia vera