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Sandra Jacinto1, Rita Lopes da Silva1, Ana Isabel Dias1, José Pedro Vieira1, Ana Moreira1, Fátima Furtado2, Ana Cristina Ferreira3, Sílvia Sequeira3, Carla Conceição4, Manuela Grazina5, Eulália Calado1


1- Pediatric Neurology Department, Hospital Dona Estefânia, Centro Hospitalar de Lisboa Central, EPE, Lisbon;
2- Pediatric Department, Hospital José Joaquim Fernandes, Unidade Local de Saúde Baixo Alentejo, EPE, Beja;
3- Metabolic Diseases Unit, Hospital Dona Estefânia, Centro Hospitalar de Lisboa Central, EPE, Lisbon;
4- Imaging Department, Hospital Dona Estefânia, Centro Hospitalar de Lisboa Central, EPE, Lisbon;
5- Center for Neuroscience and Cell Biology – University of Coimbra, Coimbra

- 10th International Symposium SPDM, Cascais, 20 e 21 de Março de 2014 (comunicação oral)

Introduction: Mitochondrial disorders are multisystemic diseases, characterized by a wide spectrum of clinical manifestations. The nervous system and the muscle, as highly energy-dependent tissues, are frequently affected. As a reflection of dysfunction of any part of the nervous system, several neurological presentations are possible.

Results: We describe the clinical, biochemical, imagiological, histological and genetic characteristics of 14 children diagnosed with mitochondrial disease, followed in a Pediatric Neurology Department. Only patients with a defect in the enzymatic activity and/or molecular diagnosis were included. Median age was 6,5 years (range 10m-16y), with 3 pairs of siblings affected. Encephalo(myo)pathy and developmental delay/regression were the main presentation features 11/14 (78%) . Seizures were present in 6 (43%) children. One patient presented with myopathy (Kearns-Sayre syndrome) and other with pure neuropathy (Charcot-Marie-Tooth). Other present features were neurosensorial deafness, short stature, cardiac A-V block and diabetes. Brain MRI findings were diverse, the more frequent being Leigh syndrome and white matter changes. Five patients had muscle biopsy performed. Reduced activity of respiratory chain complexes was present in 8 patients. Molecular diagnosis was achieved in 8 patients, with 2 pathogenic mtDNA mutation/rearrangement identified, mtDNA depletion in 2 and 4 patients with nuclear gene defects (PDH deficiency in 3 patients and MFN2 in 1 patient with Charcot-Marie Tooth).

Comments: Our sample reflects the clinical heterogeneity, as well as different inheritage pattern and age of presentation. Mitochondrial disorders are probably underdiagnosed in our population of patients. We believe that the dimension of our sample reflects the difficulty in diagnosing these disorders using clinical features alone. Invasive tests (particularly muscle biopsy) and complex genetic studies remain essential tools in the diagnostic investigation.

Palavras Chave: Doenças Mitocondriais, Leigh, encefalopatia, miopatia