Methylmalonic Acidemia:Report Of16Cases And Review Of The Literature

Methylmalonic acidemia is one of the most common disorders of congenital organic acid metabolism. According to the report, the morbidity of this disease is1/48000in the USA, and1/115000in Italy, and1/169000in Germany, and1/50000in Japan. Since the knowledge and newborn screening of this disease is lacking, there are many difficulties with diagnosis and treatment. There is a high morbidity in some types. And the survivors may have left more serious neurological symptoms. So as to improve the cognition of the disease, the article summarizes the clinical features and laboratory foundations and treatment and prognosis of the disease.ObjectiveThe clinical feature of methylmalonic acidemia is complex, and characterized by neurological symptoms. This disease leads to a heavy burden for the family and society. Definitive diagnosis of methylmalonic acidemia relies on analysis of organic acids in urine by gas-liquid chromatography/mass spectrometry (GC/MS). Early diagnosis and proper treatment can effectively improve the prognosis. Because it now the limit of the experimental conditions, this kind of disease in our country hasn't screening. So be familiar with methylmalonic acidemia clinical and laboratory characteristics, and do as early as possible GC/MS urine organic acid analysis are the key of early diagnosis and treatment, thus to descending methylmalonic acidemia mortality, and improving the prognosis lay the foundation. MethodsThe16patients with methylmalonic acidemia were confirmed by gas chromatography-mass spectrometry (GC/MS) in our hospital. The87cases of methylmalonic acidemia were summarized. We divided the cases by age.Results1. The patients'age of onset ranged from5days to2years, the main manifestation:poor feeding and vomiting (37.5%), developmental retardation or degradation (37.5%), weak reaction (31.3%), convulsion (6.3%), and tachypnea (6.3%), muscular dystonia (25.0%), hepatomegaly (18.8%), skin pale (18.3%), edema and hypertension (12.5%), microcephaly (6.3%), family history positive (37.5%), metabolic acidosis (50.0%), anemia (12.5%), hematuria (18.8%), albuminuria (12.5%), leukocyturia (6.3%).2. Treatment and prognosis of our patients:Of the8cases without therapy, two patients died before the diagnosis was made,6cases died at home after giving up therapy. Seven cases received therapy of vitamin B12and supplementation of L-carmitine with restricted-protein diet,1cases failed to have follow-up. The follow-up of7cases for a period ranging from2months to2years showed a favorable outcome.3. Literature review:The87cases of methylmalonic acidemia were summarized and there were different clinical manifestations in different age groups. Patients'main manifestation between born and28days old:poor feeding and vomiting (83.7%), and tachypnea (25.6%), weak reaction (23.3%), convulsions (14.0%). Patients'main manifestation between29days old and1years old:developmental retardation or degradation (57.9%), weak reaction (42.1%), poor feeding and vomiting (31.6%), convulsions (21.1%), Patients'main manifestation with more than1years old: developmental retardation or degradation (72.0%), convulsions (44.0%), poor feeding and vomiting (24.0%), weak reaction (16.0%), psychotic behavior abnormalities (8.0%). Physical Exam:muscular dystonia, hepatomegaly, microcephaly. Laboratory examination showed metabolic acidosis, hyperammonemia, abnormal signal in basal ganglia in the cranial MRI.ConclusionsThe clinical manifestations of methylmalonic acidemia are nonspecific. The early onset form rapidly deteriorate. In the late onset form, the symptom may be quiet.