As a CpG island is present at the promoter region of its host gene, RNF130, we hypothesized that miR-340-5p is an intronic tumor suppressor miRNA epigenetically silenced by RNF130/miR-340 promoter DNA hypermethylation in multiple myeloma (Additional file 3: Figure S3). Here, RNF130 is linked to AL amyloidosis.