Prenatal diagnosis of propionic acidemia by amniotic fluid metabolites analysis using mass spectrometry

Objective To investigate the value of acylcarnitine and organic acid in amniotic fluid for the diagnosis of propionic acidemia (PA) by tandem mass spectrometry and gas chromatography-mass spectrometry (GC-MS). Methods From 2010 to 2016, 40 pregnant women with PA neonate received pregnatal diagnosis of PA in Xinhua Hospital of Shanghai Jiao Tong University School of Medicine (as PA mother group). Another 40 cases of pregnant women for conventional prenatal diagnosis at the same period were collected as control group. The pregnant women of two groups had the amniocentesis at 16-20 weeks of gestation. The levels of propionylcarnitine (C3) and acetylcarnitine (C2) in amniotic fluid were detected by tandem mass spectrometry, and the levels of methylcitrate acid and 3-hydroxypropionate were determined by gas chromatography-mass spectrometry. Part of the amniotic fluid cells were made genetic testing. Results In PA mother group, 4 fetuses were positive and the detection rate was 10%. The levels of C3 [9.53 (6.06-11.45)mmol/L], C3/C2 [1.03 (0.62-1.43)] and methylcitrate acid [3.15 (2.05-4.58) mmol/molCr] in amniotic fluid of these 4 cases were higher than those in control group[1.14 (0.52~3.40) mmol/L, 0.11 (0.05-0.22), 0.00 (0.00-0.34)mmol/molCr]. Three cases of the PA-positive children were diagnosed by gene testing. There was no significant difference of 3-hydroxypropionic acid between control group and the positive group. Conclusion For pregnant women with PA proband, the probability of children regeneration with PA is about 10%. Tandem mass spectrometry and gas chromatography-mass spectrometry can be used to detect the levels of C3 and methylcitrate in amniotic fluid, and to make prenatal diagnosis of PA. Key words: Tandem mass spectrometry; Gas chromatography-mass spectrometry; Prenatal diagnosis; Propionic acidemia (PA)