Atypical cholinesterase gene Ea: rarity in the Jamaican population - abstract

ABSTRACT

This paper reports on the rarity of the atypical cholinesterase gene Ea in the Jamaican population, via experimentally observed specific activities and percentage inhibition by dibucaine.. Homozygotes for the abnormal enzyme may develop prolonged apnoea when the muscle relaxant suxamethonium is administered prior to surgery. A total of 499 subjects were studied; of these 240 had normal serum cholinesterase activity (2669 ñ 514 mU/ml of serum) and normal dibucaine number 88. The remaining 259 subjects had lower than normal activity (1422 ñ 259 mU/ml) but normal dibucaine number 87. Homozygous carriage of the atypical gene is associated with dibucaine numbers below 20. Based upon these findings, the ensuing apnoea often caused by the abnormal enzyme (Ea) is therefore expected to be very rare among Jamaicans 25 percent of our 17 subjects who underwent suxamenthonium administration had low cholinesterase activity (1479 ñ 210 mU/ml) but had normal dibucaine number 89 and suffered prolonged apnoea, lasting from 30 to 78 minutes. These preliminary results suggest that the determination of cholinesterase activity and dibucaine numbers may not always be the most reliable criteria to differentiate the suxamenthonium-sensitive and -insensitive subjects (AU)