Existence of a silent gene for pseudocholinesterase in a Trinidad population.

Although the values reported were higher than those reported for Caucasians, differences in dibucaine number for pseudocholinesterase values among the three ethnic groups in Trinidad and Tobago, were not significant. Eight individuals had intermediate dibucaine number values between 40 and 70; one of them was African, 3 were East Indians, and 4 Mixed. Two of the Mixed group were of Portuguese lineage and had significantly lower dibucaine numbers and enzyme concentration. Two sisters of East Indian origin had an inestimable dibucaine number and their pseudocholinesterase values were just detectable, suggesting the presence of a 'silent gene' for pseudocholinesterase. These studies, which are being extended, suggest that the dibucaine number should be estimated prior to succinylcholine administration in patients in Trinidad and Tobago who are at risk of apnoea.