Comparison of gene synteny in orthologous regions from various vertebrate species. TRPC2 flanks XNDR in all species shown except chicken, in which it is apparently absent, and lizard, in which it occupies a different locus. In human, XNDR is disrupted by approximately 68 Mb of intervening sequence, while TRPC2 is a disabled pseudogene. (Gene sizes and intergenic distances are not shown to scale.).