Malignant hyperthermia-like syndrome and carnitine palmitoyltransferase II deficiency with heterozygous R503C mutation

We describe a child who developed a malignant hyperthermia-like syndrome after exposure to succinylcholine and halothane. Many features of a typical malignant hyperthermia episode were present, including tachydysrhythmia, tachypnea, and fever in association with metabolic acidosis, hyperCKemia, myglobinemia, and rapid recovery without residual effects upon administration of dantrolene, sodium bicarbonate, and active cooling. Muscle rigidity, hypercarbia, and hyperkalemia were not observed. The patient was found to be heterozygous for a mutation in the carnitine palmitoyltransferase II gene (CPT2) encoding an arginine to cysteine substitution at amino acid 503 (R503C) with reduced activity of the enzyme.