Potential mechanism of CNV-mediated variation of miRNA dosage. Schematic representation of an miRNA gene and its primary transcript (solid or dotted arrow-lines). The position of the pre-miRNA sequence is indicated as a hairpin-loop structure in the miRNA primary transcript. Dotted lines represent transcripts unlikely to be produced due to the lack of promoter and transcriptional start sequences. Orange boxes represent CNV regions (deletions, duplications and dispersed duplications). The following panels show a CNV spanning different parts of the miRNA gene: (A) whole gene, (B) 5'-portion, (C) 3'-portion and (D) intragenic region of the gene. +, - and 0 indicate potential increase, decrease and no change of miRNA dosage, respectively.