1927
Mutations in the gene encoding methyl - CpG - binding protein 2 ( MECP2 ) have been identified as clear etiological factors in more than 90 % of classical RTT cases .
 Chemical: methyl; Chemical: CpG
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: methyl; Chemical: CpG