Patent ID: 7659391

Claim:
A method for the synthesis of target-specific short double stranded RNAs of less than 30 nucleotide long comprising the steps of: a) combining a target-specific sense oligonucleotide template and a T7 RNA polymerase in a reaction mixture such that a template extended, sense oligoribonucleotide, product is formed; b) combining a target-specific antisense oligonucleotide template and T7 RNA polymerase in a reaction mixture such that a template extended, antisense oligoribonucleotide, product is formed; and c) hybridizing the sense oligoribonucleotide product obtained in step a) with the complementary antisense oligoribonucleotide product obtained in step b), characterized in that; the oligonucleotide templates of step a) and b) comprise an RNA polymerase promoter sequence consisting of the truncated T7 RNA polymerase promoter sequence as set forth in SEQ ID NO: 56, extended at the 5′-end of the template strand with the target-specific template sequence, wherein said target-specific template sequence comprises at the 5′-end two guanosine (g) nucleotides and at the 3′-end two cytosine (c) nucleotides, wherein said two cytosine nucleotides being the first two nucleotides of said promoter sequence.