Mitochondrial A3243G mutation causes mitochondrial encephalomyopathy in a Chinese patient

Abstract

Rationale: Mitochondrial mutations are associated with a wide spectrum of clinical abnormalities. More than half of these mutations are distributed in the 22 mitochondrial tRNA genes, including tRNA Leu(UUR) . In particular, the A3243G mutation in the tRNA Leu(UUR) gene causes mitochondrial encephalomyopathy. Patient concerns: A 12-year-old boy was admitted to Shaoxing People's Hospital because there is a reduction in the volume of speech, dysphonia, unable to write, recognize words, and unable to wear clothes, accompanied by unstable walking after treatment of unexplained fever and somnolence. Diagnoses: The proband underwent a thorough examination in our hospital and was diagnosed as mitochondrial encephalomyopathy. The proband carried the pathogenic heteroplasmic mutation A3243G mutation in mitochondrial 12S rRNA gene. Although his parents did not carry the mutation. Interventions: Intravenous acyclovir, ceftriaxone, and dexamethasone were used for the patient's antiviral, antimicrobial, and anti-inflammatory therapy, respectively. Intravenous mannitol was gradually tapered for reducing intracranial pressure with furosemide for inducing diuresis. Intravenous arginine could help to treat alkalosis and supple some essential amino acids. Oral oxiracetam capsules, vitamin B1, and coenzyme Q10 were used for providing nutrition and improving energy. His medications were 30 mg vitamin B1, 0.1 g vitamin C, and mecobalamin 750 μg daily after discharge from our hospital. Outcomes: The patient was able to walk and talk slowly with improved writing skills and no stroke-like episodes. The neurological examination was negative and muscle tension was identified as grade V. Lessons: Mitochondrial encephalomyopathy has different phenotypes, in addition to traditional examinations, it is important for clinicians to be familiar with genetic testing methodology as well as applications of these tests in clinic to get an accurate diagnosis.

Clinical Approaches for Mitochondrial Diseases

“…One of the most common mutation among the patients with different types of mtDNA mutations is m.A8344G, which affects the mitochondrial tRNA lysine [97][98][99][100][101]. Another prominent mutation in the same gene is m.G8363A, along with the m.A3243G, m.G3255A, and m.T3291C mutations, which have also been reported to cause MERRF with a defects in tRNA leucine [57][58][59]99,102,103]. Mutations in tRNA-coding genes induce the global impairment of mtDNA-encoded proteins rather than affecting certain complexes or pathways [101,104,105].…”

“…This can result in the overall dysfunction of mitochondria. In case studies involving MERRF patients with tRNA lysine mutations, various symptoms were reported, such as unsteadiness of gait, optic atrophy, slurred speech, sensorineural hearing loss, and limb weakness [57][58][59].…”

Clinical effectiveness of a combination of oxiracetam and traditional Chinese medicine rehabilitation program in the treatment of early stroke patients with hemiplegia

“…Oxiracetam is a drug used for the clinical treatment of cognitive dysfunction after stroke. Nevertheless, despite the effectiveness of oxiracetam in enhancing the restoration of brain tissue function in stroke patients, the drug is associated with adverse reactions, leading to poor treatment compliance [5,6].…”