Combined application of MS/MS and LC-MS/MS in the newborn screening of children with methylmalonic acidemia / 临床检验杂志

ABSTRACT

Objective To investigate the combined application value of tandem mass spectrometry ( MS/MS) and high performance liquid chromatogram-tandem mass spectrometry ( LC-MS/MS ) in the newborn screening of children with methylmalonic acidemia ( MMA ) . Methods The dried blood spot samples from the newborn with abnormal propionylcarnitine ( C3) or C3/acetylcarnitine ( C2) or C3/free carnitine ( C0) levels in the preliminary screening of MS/MS were collected, and the concentrations of MMA, methylcitric acid ( MCA) and homocysteine ( Hcy) in these samples were detected with LC-MS/MS. The neonates with increased MMA, MCA or Hcy levels were recalled, and their urinary organic acids were analyzed with gas chromatographic mass spectrometry (GC/MS). Last, gene mutation anal-ysis was performed to make a definite diagnosis.Results A total of 423 samples with abnormal C3 or C3/C2 or C3/C0 levels in the new-born screening were collected, and the positive rate of preliminary screening was about 1％. The LC-MS/MS results showed that 8 neo-nates had higher MMA and tHcy levels. The GC/MS results further showed that the level of MMA increased slightly. Conclusion The combined application of MS/MS and LC-MS/MS may increase the positive predictive value and decrease the false positive rate of MMA screening in the newborn, which may have an important clinical significane in the screening of inherited metabolic disorders.