15940
While SMN2 encodes a protein identical to SMN1 , a single nucleotide difference in exon 7 causes most of the SMN2 - derived transcripts to be alternatively spliced resulting in a truncated and unstable protein ( SMN Delta 7 ) .
 Chemical: nucleotide
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: nucleotide