Tandem repeats in IGHD locus of human (A,B), mouse (C), and common marmoset (D) IGHD loci. Duplicated and identical IGHD genes are shown by the same (nonblack) color. Dot plots were generated by the Gepard tool (Krumsiek et al. 2007). (A) The dot plot shows that the 56-kbp-long human IGHD locus contains a tandem repeat R1-R2-R3-R4 covering 24 out of 27 IGHD genes. Positions of 27 IGHD genes are shown on the left. (B) The structure of units R1–R4. (C) For better resolution, we show only a 97-kbp-long fragment of the 1.1-Mbp-long mouse IGHD loci that covers 22 out of 26 IGHD genes. The shown fragment does not cover genes IGHD4–1, IGHD5–2, and IGHD1–3 that precede the first occurrence of IGHD5-1 (the first gene in the dot plot) and a copy of gene IGHD4-1 that follows IGHD4-1 (the last gene in the dot plot). (D) A dot plot shows the 47-kbp-long IGHD locus of the common marmoset.
