We studied 31 patients suspected of having muscle carnitine palmitoyl transferase 2 (CPT2) deficiency. The catalytic activity of CPT2 was measured in muscle biopsies by the isotope exchange method and CPT2 immunoreactivity was quantitated by an enzyme-linked immunosorbent assay. Nine patients had normal enzyme activity and immunoreactivity. Eight patients had significant deficiencies in catalytic activity (> 3 S.D. below reference mean) of which six were also deficient in immunoreactivity. An additional nine patients were significantly deficient in immunoreactivity with normal catalytic activity and five patients had partial deficiencies in both. At least two categories of alterations in CPT may exist which lead to a deficiency based on the data presented: (1) a regulatory defect in CPT which only alters the enzyme active site; and (2) a structural defect due to altered synthesis, increased degradation, or changes in the immunoreactive site. It may prove to be of diagnostic importance to combine the analysis of enzyme activity and immunoreactivity in patients suspected of having a CPT deficiency and to further investigate the condition of partial CPT deficiency.
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Acknowledgements--We thank the many physicians who provided tissue from their patients for this study and Drs Linda Duffy, Richard Evans, Edward Fine and Mario Rattazzi for helpful discussion of the data and manuscript. We are also grateful to Drs James Nolan, Mark Ballow and Marie Talty for the loan of their ELISA platereaders and to Dr R. Ronchetti for his support in the early phase of this work. This work was supported in part by a grant from the Women's and Children's Research Foundation of the Children's Hospital of Buffalo. We thank Ms Patricia Jones for typing the manuscript.
Copyright 2014 Elsevier B.V., All rights reserved.
- Carnitine palmitoyl transferase
- enzyme-linked immunosorbent assay
- mitochondrial myopathy
- muscle disease