Pathogenic variants in the MDH2 gene cause a multisystem disorder.
Symptoms include epileptic encephalopathy, global developmental delay, failure to thrive, hypotonia, vision problems, gastroesophageal reflux, constipation and structural brain abnormalities.
Biochemically, patients showed elevated lactate levels with elevated lactate:pyruvate ratios. Urinary excretion showed elevations in urinary malic acid and fumaric acid.
MDH2