Interfering RNA molecules blunting

A ribonucleic acid that mediates RNA interference, comprising a double stranded structure, wherein the double stranded structure comprises a first strand and a second strand, wherein the first strand comprises a first stretch of contiguous nucleotides and wherein said first stretch is at least partially complementary to a target nucleic acid, and the second strand comprises a second stretch of contiguous nucleotides, wherein said second portion is at least partially identical to the target nucleic acid, wherein the double stranded structure is blunt end at both sides of the double strand and the length of said first strand and said first portion and the length of said second strand and said second length is 18 or 19 bases, for use in a method for treating a disease.