Effects seen when one or several genes, not specifically targeted by the siRNA or shRNA, show loss of gene expression following transfection or transduction. The sense strand of an siRNA or shRNA may be able to initiate a loss of function response from an unrelated gene. Off target effects may also refer to a secondary effect of the antisense strand of a specific siRNA or shRNA where it has the appropriate homology to knockdown the expression of another related gene that carries the same sequence.