X‐linked cardioskeletal myopathy and neutropenia (Barth syndrome): Respiratory‐chain abnormalities in cultured fibroblasts

Abstract

Conclusions The ATP production from glutamate + malate, pyruvate + malate, or succinate (+ rotenone was lower than the mean values found in control fibroblasts in patient 1 and in the low‐normal range in patient 2. Decreased activities of complex III (±30% of controls) and complex IV (±60% of controls) are in agreement with the previous studies in muscle. These findings provide evidence that respiratory‐chain dysfunction is an essential component of Barth syndrome. Results further indicate that the gene product is essential for the function, formation or stability of both complex III and complex IV. Both complex III and complex IV contain subunits that are encoded by mtDNA. The results of emetine labelling make it unlikely that the gene is involved in the expression of mtDNA. We furthermore suspect that 3‐methylglutaconic aciduria in this syndrome represents an epiphenomenon which is as yet unexplained but has been described so far in patients with separate mitochondrial disorders (Gibson et al 1995).