Patent ID: 7078196

Claim:
A method of preparing a double-stranded RNA molecule, wherein each RNA strand has a length from 19–25 nucleotides, wherein said RNA molecule is capable of target-specific nucleic acid modifications and wherein at least one strand has a 3′-overhang of 1–5 nucleotides, comprising (a) synthesizing two RNA strands each having a length from 19–25 nucleotides, wherein said RNA strands are capable of forming a double-stranded RNA molecule, (b) combining the synthesized RNA strands under conditions, wherein a double-stranded RNA molecule which mediates target-specific nucleic acid modifications is formed, wherein said double-stranded RNA molecule consists of a single double stranded region and single stranded regions of 1 to 5 nucleotides at the 3′ ends of at least one of the strands of said double-stranded RNA molecule.