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While the maternally derived X chromosome was preferentially active in the asymptomatic twin , the paternal X chromosome was active in the other, affected twin and was found in her hemizygotic nephew .
 paternal X chromosome, maternally derived X chromosome, X chromosome, X chromosome
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:
 paternal X chromosome, maternally derived X chromosome, X chromosome, X chromosome