Thirty years ago when the Japanese otolaryngologist Takahara suspected a genetic enzyme deficiency in a child whose blood from a bleeding mouth wound turned black on contact with hydrogen peroxide, he unwittingly sired pharmacogenetics, the science of interactions between genetic makeup and drugs. Many other genetic traits that are recognizable by idiosyncratic responses to drugs have come to light since Takahara's accidental observation in his acatalasic patient. Notable among these is the discovery of glucose-6-phosphate dehydrogenase deficiency among patients in whom hemolytic anemia is induced by primaquine phosphate, nitrofurantoin, phenacetin, probenecid, and other drugs.
Pharmacogenetics has two main applications. It alerts physicians to the danger of administering certain drugs to patients with genetically determined specific drug sensitivities. Equally important, it helps unveil unsuspected genetic traits, thus serving both as a diagnostic probe and as a key to a genetic marker.
A recent addition to pharmacologically identifiable genetic traits is the