A case of familial hyper-cholinesterasemia associated with isozyme variant band.

Familial cases of serum hyper-cholinesterase (chE) activity are reported. The serum chE activity in seven consanguineous members so examined proved to be elevated up to twice the normal level. In these cases, all plausible diseases that might be the culprit for the hyper-chE activity were denied by the biochemical, hormonal, and morphological examinations; fatty liver was excluded by liver biopsy. So far, there have only been two descriptions of familial cases of high serum chE activity. The serum chE isozyme analysis revealed an extra band between bands 3 and 4 only in the subjects associated with serum hyper-chE activity. No definite extra band could be detected in the serum of normal subjects or even in the subjects diagnosed as fatty liver with high level of serum chE activity. The distribution characteristics of the members with the increased chE activity and the existence of an extra band suggest that the inheritance is autosomal dominant. This is the first report to demonstrate an extra band between bands 3 and 4 in cases of familial hyper-chE. The detection of this extra band on serum chE isozyme analysis may be helpful for the diagnosis of genetically determined hyper-chE.