- The human endothelin-1 gene (EDN1) encoding a peptide with potent vasoactive properties maps distal to HLA on chromosome arm 6p in close linkage to D6S89. Hoehe, M.R., Ehrenreich, H., Otterud, B., Caenazzo, L., Plaetke, R., Zander, H., Leppert, M. Cytogenet. Cell Genet. (1993)