IDENTIFICATION OF A POINT MUTATION ASSOCIATED WITH A SILENT PHENOTYPEOF HUMAN SERUM BUTYRYLCHOLINESTERASE - A CASE OF FAMILIAL CHOLINESTERASEMIA

A point mutation which caused a silent phenotype of human serum butyry lcholinesterase (BChE) was identified in the DNA of a 47-year-old Japa nese woman who visited our hospital complaining of hypertension. The p ropositus exhibited an unusually low level of BChE activity, whereas h er younger sister and her daughter had intermediate levels of BChE act ivity and her elder sister a normal level. Immunologically, the amount of BChE protein in the serum of the propositus was normal, DNA sequen ce analysis of the propositus identified a point mutation at codon 199 (GCA --> GTA), resulting in a Ala --> Val substitution. This alterati on is one downstream codon from the catalytic active site (Ser, 198). A family study showed her younger sister and her daughter to have the same mutation. (C) 1998 Elsevier Science B.V. All rights reserved.