Plasma cholinesterase: gene and variations.

The traditional tests that have been used for the past 30 yr to determine plasma cholinesterase phenotype--measurement of esterase activity with a variety of substrates, dibucaine inhibition, fluoride inhibition, and Ro2-0683 inhibition--are inadequate for identifying some variants of this enzyme and leave many cases of prolonged response to succinylcholine unexplained. The application of the techniques of molecular genetics has permitted precise identification of plasma cholinesterase variants and has resulted in the discovery of previously unrecognized variants. It is now possible, in cases of prolonged response to succinylcholine resulting from genetically determined alterations in plasma cholinesterase, to ascertain the nature of the mutations in the alleles, and from them to deduce the structural changes in the enzymes responsible for the impairment in drug metabolism.