Figure 2

A schematic model of the expansion of the H2-T region by monogenic and multigenic tandem duplications. This model represents monogenic and multigenic tandem duplications originating from a hypothetical ancestral H2-T genomic sequence consisting of six H2-T genes. Each labeled box represents a H2-T gene in a linear array (horizontal) at different evolutionary times along the vertical axis. The horizontal double arrows labeled D1 and D2 represent the genomic products of the multigenic tandem duplication, with each product consisting of four genes.