[4 families with silent cholinesterase variant].

We report 4 patients who had apnea of variable duration after succinylcholine administration to facilitate orotracheal intubation during anesthesia. After ruling out other causes of apnea unrelated to succinylcholine, we genotyped the cholinesterase variants of these patients and their relatives measuring total plasmatic cholinesterase activity and using the inhibitors dibucaine and fluoride. We found the silent gene (Es1) both in homozygosis (2 cases) and heterozygosis, with the atypical gene (Ea11) (2 cases). The relevance of preoperative screening to prevent anesthetic accidents is emphasized.