Mitochondrial DNA 3243A>T mutation in a patient with MELAS syndrome

Abstract

Approximately 80% of cases of mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) harbor a heteroplasmic m.3243A>G transition in the tRNA^{Leu (UUR)} (MTTL1) gene. We report a MELAS case with a rare heteroplasmic m.3243A>T mutation found by direct sequencing of MTTL1. This mutation has been previously reported in 5 cases, of which 2 cases had the MELAS phenotype. Our case also strengthens the hypothesis that the m.3243A>T mutation can cause the MELAS phenotype.

Fig. 1. Sequential changes in MRI.

(a) Brain MRI on admission shows small multifocal gray matter regions in the right temporal, parietal, and occipital lobes, and diffuse white matter lesions in the left temporal lobe, visualized as high-intensity areas in FLAIR images (left). White matter lesions in the left temporal lobe show low intensity in diffusion-weighted images (right). b Extended white matter and left thalamic lesions appeared after a stroke-like episode

Fig. 2. Direct sequencing of MTTL1 from blood revealed the m.3243A>T mutation.

Sequencing chromatogram of the MTTL1 gene shows the heteroplasmic m.3243A>T mutation in the control sample and in blood, hair, nail, saliva, and fibroblasts from the patient