1719
The severe phenotype of females with tiny ring X chromosomes is associated with inability of these chromosomes to undergo X inactivation .
 tiny ring X chromosomes, chromosomes, X chromosomes
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:
 tiny ring X chromosomes, chromosomes, X chromosomes