Heterogeneity in the silent gene phenotype of pseudocholinesterase of human serum

The serum enzyme pseudocholinesterase from 14 individuals of the rare phenotype S (silent gene) has been investigated by means of various biochemical and immunological techniques. By use of more sensitive methods than standard assays, it is demonstrated that the enzyme deficiency is not complete in all cases and that certain of the sera which contain trace amounts of enzyme activity differ with respect to their immunological reactions and their electrophoretic esterase pattern.