The present disclosure provides meroduplex (nicked or gapped) ribonucleic acid molecules (mdRNA) that decreases or silences target gene expression. An mdRNA of this disclosure comprises at least three strands that combine to form at least two non-overlapping double-stranded regions separated by a nick or gap wherein one strand is complementary to a target gene RNA. In addition, the meroduplex may have one or more modifications or substitutions, such as nucleotide base, sugar, terminal cap structure, internucleotide linkage, or any combination of such modifications. Also provided are methods of decreasing expression of a target gene in a cell or in a subject to treat a disease related to altered expression of a target gene.