Methylmalonic Acidemia Complicated by Homocystinuria Diseases: a Report of Three Cases.

This study aims to improve our understanding of methylmalonic acidemia (MMA) complicated by homocystinuria disease by analyzing the clinical characteristics, treatment response and prognosis of three patients. Hyperhomocysteinemia and developmental retardation were present in all patients, epilepsy was present in one patient, and hemolytic uremic syndrome was present in one patient. The conditions of two patients were complicated by pulmonary arterial hypertension, one patient by left pulmonary vein ectopic drainage to the coronary sinus and the other by noncompaction of the ventricular myocardium. The two MMA patients with the complication of severe pulmonary arterial hypertension died because of late diagnosis and irregular treatment of MMA. Echocardiography is necessary for patients with combined MMA and homocystinuria, and these patients are susceptible to cardiovascular disease. When a patient with combined MMA and homocystinuria has the complication of severe pulmonary arterial hypertension, the prognosis is poor.