A patient (64-year-old, male) with familial cholinesterasemia caused
by
BChE deficiency was
studied. DNA sequence analysis of all exons identified a point mutation,
an A→G transition at codon
128, resulting in a Tyr→Cys substitution. The propositus showed extremely
low BChE activity, but
his other family members (three individuals) showed from intermediate to
normal BChE activity. An
immunological method revealed the absence of BChE protein in serum of the
propositus. Both PCR
primer introduced restriction analysis (PCR-PIRA) and sequence analysis
revealed all three family members to be heterozygotes for this mutation.