[Clinical and biochemical heterogeneity of childhood cytochrome C deficiency. Review of the literature].

The detailed clinical history of a patient with a partial cytochrome c oxidase (COX) deficiency, which was demonstrated both in muscle and liver tissues, is presented. The review of the 27 pediatric cases published shows the multisystemic involvement of this enzyme deficiency and its vast clinical heterogeneity. In addition to the classical findings (myopathy, Debré-DeToni-Fanconi syndrome and lactic acidosis), our patient presented: Neurosensorial hearing loss, feeding problems, failure to thrive and hypertrophic myocardiopathy. Clinical or neuroradiological findings suggestive of Leigh's syndrome were not found despite her partial COX deficiency, neurosensorial hearing loss has been observed in four other patients with COX deficiency. Therefore, this enzyme deficiency should be considered in the differential diagnosis of neurosensorial deafness in infancy.