Figure 4.

Variants of 45S rDNA sequence identified in BAC clones isolated from human chromosome 21. (A) Spatial distribution of 45S variant calls indicated separately for SNVs (above the line) and INDELs (below the line). Bars are stacked with validated and expressed variants shown in green; validated and non-expressed variants shown in dark gray; non-validated variants shown in blue. Calls from different BACs are counted separately. A variant is classified as validated if it is supported by at least 20 high-quality Illumina read alleles in at least one of the four WGS validation samples. (B) Schematic secondary structures of the human 28S rRNAs. The 28S rRNA diagrams were taken from the RiboVision Server (65). The diagram was modified to reflect the final rRNA models (66). Functional regions and variable elements of the rRNA, including ES numbering (in blue), are labeled. The consensus secondary structure was not accurately predicted for several ES loci, and the ES27L segment, with a major portion of identified variants, is not shown to scale. INDELs found in isolated human rDNA units are depicted as rectangles or arrows. Single nucleotides are shown as rectangles, multiple nucleotides are shown as arrows. Substitutions are shown as stars. Non-validated variants are shown in green and validated variants are shown in red. Additional information on identified variants in the 28S mature rRNA (primarily SNVs and short INDELs) is present in Supplementary Table S5.