Recognition of two new phenotypes segregating the E1k allele for plasma cholinesterase.

The first identification of the cholinesterase variants E1kE1k and E1kE1s is reported from a family study. The evidence is based on the biochemical parameters of enzymic activity, and dibucaine, fluoride and RO2 numbers. Two individuals appear to be homozygotes E1kE1k and two are heterozygotes E1kE1s with family evidence supportive of these genotypes. The heterozygotes E1kE1s will be sensitive to suxamethonium.