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Here, we show that the Duffy antigen/chemokine receptor gene ( DARC ) is composed of a single exon and that most Duffy-negative blacks carry a silent FY*B allele with a single T to C substitution at nucleotide -46 .
 Duffy antigen/chemokine receptor gene, exon, Duffy antigen/chemokine receptor, DARC, silent FY*B allele
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:
 Duffy antigen/chemokine receptor gene, exon, Duffy antigen/chemokine receptor, DARC, silent FY*B allele