Abstract: Objective To explore the clinical characteristics and gene analysis of methylmalonic acidemia (MMA). Methods From June 2014 to June 2017, totally 10 cases of infants were diagnosed as MMA who enrolled in Neonatal Department of Xi'an Children's Hospital of Shaanxi Province. The clinical symptoms, routine test of blood and urine, blood biochemistry index, radiology imaging, organic acids analysis of blood and urine, results of blood homocysteine and gene analysis were analyzed by retrospective analysis method. Results The main clinical manifestations of the 10 cases were poor response, unconsciousness, loss of appetite and activity, hypotonia, weak primary reflex or even disappeared, feeding difficulty, weight loss, jaundice and irregular breath. The biochemistry index showed hyperammonemia, metabolic acidosis, leukopenia, thrombocytopenia and anemia. The radiology imaging showed brain injury. The urine organic acid analysis showed elevated level of methylmalonic and blood amino acids and acylcarnitine analysis showed elevated level of C3/C2. Several of them showed increased homocysteine in blood. Four cases received gene detection, one of them genotype was mut- and the other three were cblC. Four cases of MMA were onset at birth and died shortly after birth. Six survival cases showed symptomatic improvement after treatment, but most of them had different degrees of retardation of physical development, movement and intellectual development according to the follow-up. Conclusions The clinical manifestations of the neonatal MMA are nonspecific. The neonatal MMA has an early onset and high mortality rate. The survival newborns may have brain injury. Suspicious cases should be given blood and urine amino acids test, blood homocysteine and gene analysis to make a definitive diagnosis as soon as possible. After diagnosis, long term regular and appropriate treatment should be taken so as to improve prognosis.
2018, Vol. 6 
