[Analysis of MUT gene mutations in a patient with isolated methylmalonic acidemia]

To analyze the clinical features and mutation of MUT gene in a Chinese patient with isolated methylmalonic acidemia.

The clinical characteristics and laboratory tests data were collected. Genomic DNA was extracted from peripheral blood leukocytes. The 13 exons and their flanking sequences of the MUT gene were amplified with polymerase chain reaction and subjected to direct DNA sequencing.

The patient has featured failure to thrive, lethargy, seizure, hypotonia, severe ketoacidosis and hyperammonemia. Tandem mass results showed reduction of multiple acylcarnitine. Urine organic acid testing showed pronounced increase in methylmalonate excretion. Homocysteine was normal. The patient showed no response to vitamin B12 treatment. The above results suggested that the patient had isolated methylmalonic acidemia. DNA sequencing analysis confirmed that the patient has carried two MUT gene mutations, c.755dupA and a novel mutation c.944dupT.

Inherited metabolic disease screening plays an important role in the diagnosis of clinical diseases. However, to confirm the results will need gene mutation analysis.