[Phenotype heterogeneity associated with mitochondrial DNA A3243G mutation].

Objective: To discuss the clinical characteristics associated with mitochondrial DNA A3243G mutation.
Methods: Clinical manifestations as well as results of brain CT and/or MRI scanning, blood level of lactic acid and muscle biopsy results of 25 mitochondrial encephalomyopathies patients whose A3243G mutations were analyzed.
Results: Although all of the 25 patients carried mtDNA A3243G point mutation, their clinical manifestations varied greatly. Among them, there were 19 cases of mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS), 2 cases of encephalopathies which could not be classified into any specific type, 2 cases of floppy infants, one case of Kearns-Sayer syndrome (KSS) and one case of mitochondrial entero-myopathy. Most patients showed abnormal cranial radiological findings and ragged-red-fibers on muscle biopsies. Elevation of blood lactic acid was notably found in all of the 25 patients.
Conclusions: Significant variations in clinical manifestation and brain images are the prominent features in patients with A3243G mutation. Mitochondrial diseases should be considered in patients with multiple organ involvement and elevated serum lactic acid mtDNA mutation examination is necessary for the diagnosis of mitochondrial diseases.