Figure 1.

CNVs may influence phenotype though several mechanisms. A gene duplication or deletion event can alter the expression of dosage-sensitive genes. CNVs that only partially overlap a dosage-sensitive gene can induce reduced expression, or by disrupting structure, lead to novel transcripts. CNVs can regulate normal flanking genes, often through a distal mechanism that can extend several megabases from the breakpoints, by modifying regulatory elements. CNVs can also regulate the expression of target genes through position effects (i.e. through the insertion or deletion of sequences leading to alterations in distance to regulatory elements). Green boxes represent exons. Blue boxes represent promoters while orange boxes represent distal enhancers. Triangles mark the breakpoints of CNVs. Circles represent transcription factors that may bind to regulatory elements. (A colour version of this figure is available online at: http://bfg.oxfordjournals.org)