ferase (HNMT) enzyme and gene. In: Falus A, ed. Histamine: biology and medical aspects. Budapest, Hungary: SpringMed Publishing, 2004:53-9. 37. 4-1 Yamauchi K, Sekizawa K, Suzuki H, et aL Structure and function of human histamine N-methyltransferase: critical enzyme in histamine metabolism in airway. Am J