Mitochondrial disease criteria: diagnostic applications in children
E Morava1, L van den Heuvel, F Hol
1Department of Pediatrics, Nijmegen Centre for Mitochondrial Disorders, Radboud University Medical Centre Nijmegen, PO Box 9101, 6500 HB Nijmegen, the Netherlands. E.Morava@cukz.umcn.nl
Background:
Based on a previous prospective clinical and biochemical study, a consensus mitochondrial disease scoring system was established to facilitate the diagnosis in patients with a suspected mitochondrial disorder.
Objective:
To evaluate the specificity of the diagnostic system, we applied the mitochondrial disease score in 61 children with a multisystem disease and a suspected oxidative phosphorylation disorder who underwent a muscle biopsy and were consecutively diagnosed with a genetic mutation.
Methods:
We evaluated data of 44 children diagnosed with a disorder in oxidative phosphorylation, carrying a mutation in the mitochondrial or nuclear DNA. We compared them with 17 children who, based on the clinical and metabolic features, also had a muscle biopsy but were finally diagnosed with a nonmitochondrial multisystem disorder by further genetic analysis.
Results:
All children with a genetically established diagnosis of a primary oxidative phosphorylation disorder had a mitochondrial disease score above 6 (probable mitochondrial disorder), and 73% of the children had a score above 8 (definite mitochondrial disorder) at evaluation of the muscle biopsy. In the nonmitochondrial multisystem disorder group, the score was significantly lower, and no patients reached a score comparable with a definite respiratory chain disorder.
Conclusions:
The mitochondrial disease criteria system has a high specificity to distinguish between mitochondrial and other multisystem disorders. The method could also be applied in children with a suspected mitochondrial disorder, prior to performing a muscle biopsy.
