DEMONSTRATION OF AN ENZYME VARIANT IN A CASE OF CONGENITAL METHAEMOGLOBINAEMIA

A partially purified protein extract was prepared from the red cells of a patient with congenital methemoglobinemia and from normal individuals. Electrophoresis of these extracts at pH 8.6 and staining with a 26-dichlorophenolindophenol/reduced NAD system showed two decolorized bands of diaphorase activity in normal individuals and a single band of intermediate mobility in the patient. The mother of the patient showed both normal and abnormal enzymes. The enzyme deficiency in this patient may be the result of the synthesis of an abnormal form of reduced NAD linked methemoglobin reductase.