A novel mitochondrial transfer RNA(Asn) mutation causing multiorgan failure.

BACKGROUND Mitochondrial cytopathies are a heterogeneous group of disorders with a broad spectrum of clinical symptoms. OBJECTIVE To characterize a novel mutation in the transfer RNA(Asn) (m.5728A>G) identified in a 13-year-old boy with multiorgan failure. DESIGN Biochemical and immunocytochemical studies were performed in combination with transmitochondrial cybrid analysis. SETTING A university hospital. Molecular and biochemical analyses were performed in collaboration between 2 other university hospitals. PATIENT Thirteen-year-old boy with multiorgan failure. RESULTS In the patient's muscle tissue and cultured skin fibroblasts, a combined deficiency of complexes I and IV was found, using spectrophotometric analysis and activity staining in the gel following blue native polyacrylamide gel electrophoresis. An identical biochemical profile was seen in transmitochondrial cybrids carrying more than 55% mutant mitochondrial DNA. CONCLUSION These data suggest that the m.5728A>G transition is a pathogenic mutation and is the cause of the respiratory chain dysfunction in the propositus.