DDT, D-dopachrome tautomerization, converts D-dopachrome into 5,6-dihydroxyindole. Northern blot analysis revealed that DDT was expressed as a 0.6-kb mRNA in all tissues tested, with the strongest expression in liver. The DDT gene in human and mouse is identical in exon structure to the MIF gene. Both genes have 2 introns that are located at equivalent positions, relative to a 2-fold repeat in protein structure.the genes for DDT and MIF are closely linked on human chromosome 22 and mouse chromosome 10.