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Abstract: FR-PO272

Genotype, Not Lactic Acidosis, Predicts Disease Progression in a Cohort of MELAS Patients

Session Information

Category: Fluid and Electrolytes

  • 902 Fluid and Electrolytes: Clinical


  • Moturi, Krishna rekha, John H. Stroger Jr. Hospital of Cook County, Chicago, Illinois, United States
  • Jin, Jifu, Zhongshan Hospital, Shanghai Medical College, Fudan University, Shanghai, China
  • Li, Jiangtao, Tongji Hospital, Tongji University School of Medicine, Shanghai, China
  • Gavrilova, Ralitza H., Mayo Clinic, Rochester, Minnesota, United States
  • Qian, Qi, Mayo Clinic School of Medicine, Rochester , Minnesota, United States

The clinical features of MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes) are heterogeneous. The role of lactic acidosis and MELAS genotypes in disease severity and progression has not been clarified. This study investigated MELAS phenotype in relation to the presence/severity of lactic acidosis and to the MELAS genotypes (classic [m.3243A>G] and other non-classic mutations).


MELAS patients in the North American Mitochondrial Disease Consortium (NAMDC) database, hospitalized in the Mayo Clinic for MELAS-related symptoms (up to Jan. 2018), were enrolled. Demographics, disease course, laboratory results, neuroimaging and muscle biopsies were obtained.


Twenty-four (24) participants (15 female) were studied. Total follow-up was 170 person-years (median follow-up, 7.2 [IQR 1.3-11.6] years). The median age of disease onset was 6.5 (IQR 1.0-35.2) years. Headache, confusion, and ↓cognition were the most common initial presentations. 16.7% of the subjects died during the follow-up. Lactic acidosis, defined by serum lactate >2.2 mmol/L, was present in 83.3% of the patients with an average serum level 3.3±1.0 mmol/L. No significant association was found between the presence and severity of lactate levels and MELAS disease presentation and progression.
33.3% and 66.7% of the subjects harbored m.3243A>G and non-classic mutations, respectively. Patients with m.3243A>G mutation had a higher % occurrence of diabetes, hearing loss, cognitive dysfunction, migraine, seizures and stroke-like episodes and a lower % occurrence of skeletal myopathy than the patients with non-classic mutations, 50 vs 6.3; 100 vs 25; 87.5 vs 31.3; 75 vs 31.3; 100 vs 56.3; 75 vs 12.5; 12.5 vs 68.8, respectively (all P<0.05). Despite more aggressive treatment with antiepileptic, L-arginine and CoQ/Q10, cardiac functional and cognitive deterioration were more rapid and severe in patients with m.3243A>G mutation (all P<0.05). More diagnostic tests (CSF lactate, muscle biopsy and MRS) were performed for patients with non-classic mutations (P<0.05).


In this cohort of MELAS patients, the m.3243A>G mutation, not the presence or severity of lactic acidosis, was associated with a more severe MELAS phenotype.