Hidaka_1997_Clin.Chim.Acta_261_27

A point mutation that causes a silent phenotype for human serum butyrylcholinesterase (BChE) was proved by DNA analyses of a 64-year-old Japanese female who visited the hospital because of a common cold. The propositus and her two siblings showed extremely low BChE activity, but other family members (six individuals) manifested from intermediate to normal values of BChE activity. An immunological method revealed that the propositus and her two siblings showed absence of the BChE protein in serum. DNA sequence analysis of the propositus identified a point mutation at codon 400 (TGC-->TGA), resulting in the production of a stop codon. This alteration exists upstream of the Cys571 of the subunit, which forms a disulfide bridge with the Cys571 of another partner subunit.