12664
The rapid expansion of the number of women now suitable for X inactivation analysis has however given rise to new controversies, one of the more troublesome being the possibility of a modification of the pattern of X- chromosome inactivation pattern in blood cells of elderly women .
 ( DNA: X- chromosome, None) , ( cell type: blood cells, None) 
Locate the role in the text that participated in the event based on the event type and return it in the event list. 
 Option: Event type: RNA,cell type,protein,cell line,DNA, Arguments type: . 
Text: {0} 
Answer:
 ( DNA: X- chromosome, None) , ( cell type: blood cells, None) 