Diagrams of chromosome 15q11-q13 gene order and expected expression patterns in duplication of 15q11-q13 (dup15q) and control samples based on copy number and parental origin. The paternal chromosome is shown in blue and the maternal chromosome in red. Genes are listed and color blocks match, respectively, to model the location on the chromosome with the orientation indicated by arrows. Red × marks represent silencing from parental imprinting. The table at the top lists total genomic copies and the number of copies of each gene and color code: small nucleoriboprotein N (SNRPN), green; ubiquitin ligase 3A (UBE3A), yellow; and GABAA receptor β3 (GABRB3), purple. (a) Control (CTRL), (b) interstitial duplication of 15q (int dup(15q)) has one additional copy, (c) isodicentric duplication of chromosome 15 (idic(15q)) has two additional maternal copies of the locus and (d) the tricentric supernumerary chromosome 15, which contains four additional copies of chromosome 15.