The invention relates to double-stranded ribonucleic acid (dsRNA) targeting a PROC gene, and methods of using the dsRNA to inhibit expression of PROC. At least one nucleotide of the dsRNA can be a modified nucleotide, e.g., a 2-0-methyl modified nucleotide, a nucleotide comprising a 5′-phosphorothioate group, and a terminal nucleotide linked to a cholesteryl derivative or dodecanoic acid bisdecylamide group. Other examples of modified nucleotides include a 2′-deoxy-2′-fluoro modified nucleotide, a 2′-deoxymodified nucleotide, a locked nucleotide, an abasic nucleotide, 2′-amino-modified nucleotide, 2′-alkyl-modified nucleotide, morpholino nucleotide, a phosphoramidate, and a non-natural base comprising nucleotide. A dsRNA of the invention can include one or more of any of these modified nucleotides.