E1k, another quantitative variant at cholinesterase locus 1.

Two families segregating for the atypical (E1a) allele at cholinesterase locus 1 are described. Unusual results for dibucaine inhibition led to the recognition of a new allele (E1k) also segregating in these families. The enzymatic and immunological data are consistent with the hypothesis that E1k causes reduction of 'usual' (E1u) molecules by about 33%. Whether the reduction of E1u caused by E1k is caused by retarded synthesis or accelerated degradation of serum cholinesterase remains to be determined.