Biochemical and molecular correlations in carnitine palmitoyltransferase II deficiency.

Carnitine palmitoyltransferase II (CPT II) deficiency is the most common lipid myopathy in adults and is characterized by exercise-induced pain, stiffness, and myoglobinuria. Retrospective analysis of patients with CPT II deficiency has made it possible to correlate the presence of disease-causing mutations in the CPT2 gene with residual CPT activity in muscle. We present evidence that the ratio of CPT II activity to citrate synthase activity in the skeletal muscle of patients presumed to have CPT II deficiency is important for predicting whether the patient has one, two, or no mutations in the CPT2 gene. This finding will assist in the future correlation of the phenotype with the genotype and in identifying manifesting heterozygotes.