A new variant of butyrylcholinesterase gene detected in two patients in Yamaguchi Prefecture

「ABSTRACT」Two unrelated Japanese patients, a 56-year-old male and a 59-year-old female, showed extremely low butyrylcholinesterase (BChE) activity in their sera and seemed to be homozygous for a silent type of the BChE gene. Production of the BChE protein could not be found in their sera by an immunological method. DNA sequence analysis identified a point mutation at codon 100 (CCA→TCA), resulting in a Pro→Ser substitution. A new Mva I restriction site was introduced into the PCR product of a normal subject by PCR-primer introduced restriction analysis (PCR→PIRA)using a specific mismatched primer. This PCR-PIRA method thus enabled us to distinguish clearly this mutation from the normal allele. 「Introduction」Human serum butyrylcholinesterase (BChE) is characterized clinically because of its function of hydrolysis of the muscle relaxant succinylcholine (SCC), used in surgical operations as an anesthetic. Individuals homozygous for hereditary serum BChE deficiency have an abnormal response to administration of SCC in a standard dose, resulting in prolonged apnea, which may be due to the reduced affinity of BChE variant for this substrate, but it is harmless to the carrier in daily life.