FIG. 4.

Effect of changing the position of a second mismatched base on allele-selective inhibition of HTT. (A) Table of ss-siRNAs. Subscript “_s” indicates PS linkage; 2′-O-Me modified base is shown in uppercase; 2′-F in underlined uppercase; 2′-MOE in enclosed box. Mismatched base is shown in bold and italic. The terminal T has a 5′ phosphate. ND: not determined. (B) Inhibition of HTT expression by ss-siRNAs tested at 25 nM concentrations. (C) Effect of increasing concentrations of ss-siRNAs ISIS 618381 and ISIS 618385, representative data from triplicate experiments. CM: non complementary duplex RNA. NT: no treatment.