1154
BACKGROUND: Understanding the mechanism of developmental regulation of hemoglobin switching has scientific as well as clinical relevance because of the influence of fetal hemoglobin ( HbF ) production in adulthood on the clinical manifestation of thalassemia and sickle cell anemia .
 hemoglobin, HbF, hemoglobin
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: cell line, protein, RNA, DNA, cell type 
Text: {0} 
Answer:
 hemoglobin, HbF, hemoglobin