6403
We studied the functional interaction between human embryonic zeta 2 globin promoter and the alpha globin regulatory element ( HS - 40 ) located 40 kb upstream of the zeta 2 globin gene .
 zeta 2 globin, alpha globin regulatory element, HS - 40, zeta 2 globin gene
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: GENE 
Text: {0} 
Answer:
 zeta 2 globin, alpha globin regulatory element, HS - 40, zeta 2 globin gene