Retrospective analysis of diagnosis and treatment in 9 cases of childhood-onset methylmalonic acidemia in China

Early-onset MMA is more common, and its clinical manifestations are non-specific. Clinicians should be vigilant about genetic metabolic etiologies in patients with early-onset MMA characterized by recurrent seizures and developmental delay, late-onset MMA with mental and behavioral abnormalities or consciousness disturbances, and those with abnormal metabolic indicators. It is recommended to actively perform blood and urine tandem mass spectrometry and genetic analysis to confirm the diagnosis. The <i>MMACHA</i> c.658-660del (p. Lys220del*) variant may be associated with a poor prognosis in MMA patients.