[Screening for neonatal inborn errors of metabolism by electrospray ionization-tandem mass spectrometry and follow-up].
OBJECTIVE
To determine the impact of expanded newborn screening using tandem mass spectrometry (MS/MS) on the overall detection rate of inborn errors of metabolism in Zhejiang province and to assess the outcome of the patients who were diagnosed.


METHODS
Blood spots were collected between days 3 and 6 of life from the newborns. All samples were subjected to MS/MS analysis using Waters Quattro API. Confirmation tests included amino acid analysis, urinary organic acids by GC-MS, routine blood analysis, biochemistry, blood gas analysis, blood glucose and ammonia tests, blood homocysteine, lactate and pyruvate tests, urine acetone tests, biotin and biotin enzyme profile and DNA analysis. Standard treatment protocol was given to the patients. Protein restricted diet, special powdered formula and medicines recommended for the patients with amino acidemias. Protein restricted diet and L-carnitine, folic acid and Vitamin B12 supplementation were given for the patients with organic acidemia. L-carnitine was given to the patients with primary carnitine deficiency. The overall epidemiology, prognosis, follow-up of the screening program were also investigated in the neonates.


RESULTS
A total of 129 415 neonates were investigated for 26 inborn errors of metabolism during the period. Twenty-three newborns were confirmed as having inborn errors of metabolism, including 13 with amino acidemias, 6 with organic acidemias and 4 with fatty acid oxidation disorders. The prevalence was 1:5626. Positive predictive value was 2.10%, specificity was 99.72% and sensitivity 100%. Seventeen children remain asymptomatic during the follow-up. Five patients had motor and mental developmental delay. One patient presented metabolic disorders during the follow-up. No death occurred in this series of patients.


CONCLUSIONS
This strategy represents a valuable preventive medicine approach by enabling diagnosis and treatment before the onset of symptoms.
Department of Genetic and Metabolic Diseases, the Children's Hospital, Zhejiang University School of Medicine, Hangzhou 310003, China.
Xin-wen
XW
Huang
Jian-bin
JB
Yang
Fan
F
Tong
Ru-lai
RL
Yang
Hua-qing
HQ
Mao
Xue-lian
XL
Zhou
Xiao-lei
XL
Huang
Li-li
LL
Yang
Cheng-gang
CG
Huang
Zheng-yan
ZY
Zhao
D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D008661:Metabolism, Inborn Errors / Q000175:diagnosis* / Q000378:metabolism; D015997:Neonatal Screening / Q000379:methods*; D021241:Spectrometry, Mass, Electrospray Ionization; D053719:Tandem Mass Spectrometry