The HOX complex neighbored by the EVX gene, as well as two other homeobox-containing genes, the GBX-class and the EN-class, are located on the same chromosomes 2 and 7 in humans.

Two newly identified human homeobox-containing genes, GBX1 and GBX2, are closely related genes, as are members of the other homeobox genes, EN-1 and EN-2. GBX1 and EN-2 have been mapped to chromosome 7q36. The present study shows that GBX2 was mapped to chromosome 2q37. EN-1 was mapped to chromosome 2q14. Moreover, two HOX complexes neighbored by the EVX gene, HOXA and HOXD, are located at chromosome 7p15-p14 and 2q31-q37, respectively. Thus, it is possible that these homeobox genes were linked to each other on an ancestral genome and that the ancestral chromosome segment was duplicated during evolution.