Introduction Respiratory chain disorders (RCD) are a heterogeneous group of diseases associated with multisystemic disorders. The diagnosis should be considered if there are 2 major criteria or 1 major and 2 minor criteria (Modified Walker Criteria).
Purpose Medical records of 16 cases of RCD diagnosed in Metabolic Unit of our hospital, between 2005 and 2010 were analyzed.
Results The results showed that all the patients have psychomotor delay and more than half cases hypotonia, strabism and adquired microcephaly at presentation. Other symptoms were multisystem such as: neurossensorial deafness (1/16), mioclonic epilepsy (3/16), intestinal duplication (1/16), ductus arterious persistent (1/16), renal hypopasia (2/16). We found important association with endocrinological changes (9/16), hypothyroidism in most situations, but also hypoparathyroidism, insipidus diabetes, growth hormone defect and hyperinsulinemia. Complex 2 deficiency was the most common cause of RCD (8/16). In one case we found depletion in mitochondrial DNA. No histopathology abnormalities were found in the muscle biopsy. Only (8/16) exhibited elevated plasma lactate. The treatment with Coenzyme Q10, carnitine and ketogenic diet seemed to improve their clinical course (less epileptic crisis after ketogenic diet – 6/6, better concentration after coenzyme Q10 – 6/16, less hypotonia after carnitine – 5/11).
Discussion and conclusion Mitochondrial cytopathies should be considered in patients with an unexplained combination of neuromuscular and/or nonneuromuscular symptoms, with a progressive course, even if oxphos studies are normal.
Endocrinological changes are an important association of respiratory chain disorder and hormone screening must be included in all the patients with this metabolic disease.