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After first strand cDNA synthesis from fetal brain mRNAs , short fragment cDNAs ( sf - cDNAs ) were synthesized with a two - step amplification system by use of our modified Degenerate Oligonucleotide Primed Shuttle Polymerase Chain Reaction ( DOP - Shuttle - PCR ) method .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: GENE 
Text: {0} 
Answer:
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