Mitochondrial disorders - A proposal for consensus diagnostic criteria in infants and children

Background: In 1996 diagnostic criteria were published for adults with respiratory chain disorders. Modified criteria for children were also recently proposed. Objective: To facilitate and standardize diagnosis of respiratory chain disorders in children. Methods: A new classification has been developed, the Mitochondrial Disease Criteria (MDC), for the diagnosis of respiratory chain disorders in infants and children. It considers clinical, metabolic, imaging, and histopathologic features vs biochemical investigations of skeletal muscle. The criteria were applied to a group of 30 children. Results: The modified adult criteria and the MDC gave similar results, with 17 patients having a definite respiratory chain disorder. No patients reached this category using the original adult criteria. Conclusions: The proposed Mitochondrial Disease Criteria classification allows more precise definition of clinical and metabolic items and the independent scoring of muscle biochemical investigations before combining all findings to determine the overall diagnostic certainty.