Population and pharmacogenetic studies on serum cholinesterase (E): estimates of theE 1 andE 2 allele frequencies for the population of Central Italy,and of the correlation between E activity and sensitivity to succinylcholine (SCC)

392 random patients treated with SCC prior to surgery were assayed for pseudocholinesterase activity and electrophoretic pattern. The estimate of the percent frequencies of theE ₁ ^a allele were 1.16±0.38 and of the C₅ (+) phenotype 9.7±1.5, both typical of Caucasian populations. By combining the presentE ₁ ^a gene frequency estimate with that from another sample of the same population (Cermele et al., 1987) a better estimate with smaller confidence limits was obtained, that is: 1,14±0,27. One subject interpreted asE ₁ ^a E ₁ ^a on phenotypic grounds was also found (expected 0,05) in this random sample. A correlation coefficient of −0.521 was found between E activity and myorelaxation time in the whole sample. High correlation values (r=−0.55 and r=−0.46) were found forE ₁ ^u E ₁ ^u ; C₅ (−) andE ₁ ^u E ₁ ^u ; C₅ (+) individuals, respectively, showing a strong dependence of the latter variable on the former one even within apparently homogeneous classes. The use of the product of these two variables as a classification criterion allowed the identification of a subject with very long myorelaxation time but normal activity.