Hypercholinesterasemia with isoenzymic alteration in a family

A family with hypercholinesterasemia with isoenzymic alteration is reported. The propositus, a 55-year-old woman, was admitted to our hospital because of diabetes mellitus. Because her cholinesterase activity (delta pH 3.2) was supranormal, with no other abnormal liver-function test result throughout the hospitalization period, and was independent of her disease state, we investigated whether this condition might be familial. We studied six of her 17 family members in three generations. All six had above-normal serum cholinesterase activity. Gradient gel electrophoresis on polyacrylamide showed that the normal control individuals had seven isoenzymes, but all the family members with hypercholinesterasemia had two additional isoenzymes. The enzymic properties of the affected members were similar to those of the normal individuals. Hypercholinesterasemia in this family seems to be the result of an increased number of enzyme molecules, but how this isoenzymic alteration emerged remains obscure.