Patent ID: 7745608

Claim:
An iRNA agent comprising a first strand and a second strand, wherein at least one subunit having a formula (I) is incorporated into at least one of said strands, and at least one of said strands leads to the cleavage of a complementary target sequence via a RISC dependent mechanism: wherein: X is N(CO)R 7 , or NR 7 ; R 3 and R 9 are each independently H, OH, OR a , or OR b , provided that only one of R 3 or R 9 is OH, OR a , or OR b ; R 5 is H or C 1 -C 6 alkyl; R 7 is C 1 -C 20 alkyl substituted with NR c R d or NHC(O)R d ; R a is R b is each of A and C is, independently, O or S; and B is OH, O − , or R c is H or C 1 -C 6 alkyl; and R d is a steroid radical, which is optionally tethered to at least one carbohydrate radical.