The effect of temperature on fluoride-resistant serum cholinesterase.

By means of dibucaine inhibition (Kalow and Genest, 1957) it was found possible to differentiate three inherited serum cholinesterase phenotypes, those homozygous for the usual enzyme, homozygotes of the atypical enzyme and heterozygous individuals (Kalow and Staron, 1957). Harris and Whittaker (1961) then showed that sodium fluoride could be used to differentiate the serum cholinesterase variants in a manner similar to that of dibucaine. In a study of suxamethoniumsensitive patients and their families, Harris and Whittaker (1961) found that fluoride inhibition revealed two further groups. Later studies (Harris and Whittaker, 1962, 1963) showed that these were the results of another allelic gene which was termed fluoride-resistant. Lehmann and associates (1963) first reported the existence of the phenotype homozygous for the fluoride-resistant gene. The occurrence of three further cases has been reported (Liddell, Lehmann and Davies, 1963; Whittaker, 1964; Griffiths, Davies and Lehmann, 1966). Lehmann and Liddell (1969) have estimated that the fluoride-resistant homozygote occurs once in 300,000 of the population and thus is the rarest of the cholinesterase variants.