A secondary respiratory chain defect in a patient with Fanconi-Bickel syndrome.

A North African boy, the son of consanguineous parents, presented at 8 years of age with hypophosphataemic rickets due to De Toni-Debré-Fanconi syndrome. Hepatomegaly and abnormalities of carbohydrate metabolism were suggestive of Fanconi-Bickel syndrome. This was confirmed by the detection of a mutation within GLUT2, the gene encoding the liver-type facilitative glucose transporter. The study of the respiratory chain revealed a deficiency of complexes I, III and IV in muscle. Mechanisms responsible for an impairment ofmitochondrial function, which we interpret as a secondary phenomenon, are discussed.