Report Of Two Cases Late-Onset Methylmalonic Aciduria And Review Of The Literature

Objective:Methylmalonic aciduria (MMA), also called Methylmalonic acidemia, as a kind of autosomal recessive hereditary disease, is one of the most common disorders of hereditary organic acid metabolism. While multi-organ pathology is a feature of MMA, such as the nervous system, liver, kidney, bone marrow, its clinical manifestations are complicated. Supposing that timely diagnosis and reasonable treatments are not obtained, MMA will bring enormous suffering and burden to patients, families and society. So as to improve the cognition of MMA, the article summarizes the clinical features, auxiliary examinations, treatment regime, prognosis and preventions.Methods:The two patients with methylmalonic acidemia were confirmed by genetic diagnosis, combining with literature review,the article summarizes the clinical features, auxiliary examinations, treatment regime, prognosis and preventions of MMA.Result:One case presents a young women for pregnancy, with features of Chronic episode and repeated courses, was admitted to hospital for mental behavior disorder, mental behavior, seizures, walking instability as the main symptoms. Related auxiliary examination revealed that giant cell anemia, homocysteinemia. EEG showed slight abnormal eeg. Cranial MRI scanning displays that abnormal signal in basal ganglia, Bilateral brain atrophy in frontal and parietal, Pons central abnormal signal. Gene analysis and outcomes confirm for MMA. The main treatment for MMA patients is AEDs, blood transfusion, Vitamins B(B1, B6, B12)and methylprednisolone, nutritional supportting, induction of labor and so on. Symptoms improved significantly after discharge, the patient also received therapy of vitamin B12 and supplementation of L-carmitine with restricted-protein diet. The other case presented a 14-year-old girl, started with mental behavior, seizures, walking instability, nausea, vomiting. Auxiliary examination:Cranial MRI enhancement scanning showd bilateral diffuse edema in cerebellar hemispheres, which considerring inflammatory lesion. EEG showed slow background activity. Gene diagnosis confirm for MMA. The treatment regime:dexamethasone, carnitine injection,VitB12, VitBl and other supportting therapy,The patient symptoms improved after treatment.Conclusion:(1)Methylmalonic aciduria is relatively rare and it’s an autosomal recessive hereditary disease, its clinical manifestation is complicated, often cause multiple systems or organs lesions. (2) According to the different onset age, MMA divided into early-onset and late-onset. The early-onset form can be rapidly deteriorate. However, the symptom of late onset may be quiet. (3)The related auxiliary examination displayed homocysteinemia, metabolic-acidosis, hyperammonemia and ect. besides the other nonspecific symptoms. Cranial MRI scanning can show typical and nonspecific changes. Organic acid test of urine can be used in the diagnosis of the disease and also can be used as an effectively sensitive index for vitamin B12 treatment. Moreover, gene diagnosis is helpful to clinical diagnosis and prenatal diagnosis. (4) The main treatment for MMA patients is the dietary restriction of propiogenic amino acids and carnitine supplementation, a supplements of vitamin B12 for vitamin B12-responsiveness, regularly test the content of methyl malonic acid urine. (5) MMA mortality rate is high, and the prognosis is disappointing.