The Application Of Cord Blood Capillary Electrophoresis For Screening Of Neonatal Thalassemia

【Objective】1. To investigate the ability of the capillary electrophoresis detection of Hb Bart’s andHb A in the umbilical cord blood, gene results were obtain by Luminex200suspension array system, use the gene as the gold standard, to access the ability ofscreening of α-thalassemia and β-thalassemia.2. To obtaine the prevalence of α-thalassemia and β-thalassemia in neotates inGuangdong Province through gene diagnose.【Methodology】1. Sampling methods：During May2012to December2012, we selected one countywhich had the birth defects monitoring in each of the21cities of Guangdong Province,then, in each of the county,91hospitals were selected (which the numbers of deliverywere more than600yearly), and from the hospitals above, the total qualifiedumbilical cord bloods were13396.2. Hemoglobin fractions and quantification were performed using capillaryelectrophoresis (capillary2), to abtain the concentration of hemoglobin A, F, Hb A2and Hb Bart’s.3. Using the Luminex200suspension array system to detect the twenty-threecommon mutations including three deletion mutations of α-thalassemia, three non-deletional mutations of α-thalassemia, and seventeen point mutations ofβ-thalassemia.4. ROC curve was used to the evaluation for capillary electrophoresis screening ofneonatal β-thalassemia, and to get the best cut-off value of Hb A.5. Statistical calculations were performed with SPSS13.0for Windows computersoftware. Values were reported as median and25-75percentiles. The relationshipbetween the percentages of Hb A with gestational age was evaluated by calculatingthe Spearman coefficient. Using Mann-Whitney U-test to compare the percentage ofHb A in the different group.【Result】1. Totally, in the13396samples of the umbilical cord blood, by DNA testing,1571cases are α-thalassemia,500cases are β-thalassemia.76cases are α compoundβ-thalassemia. The prevalence of neonatal thalassemia are16.03%.2273cases are αand β thalassemia gene deletions and mutations, the prevalence of carries ofthalassemia mutation gene are16.97%. And1692are α-thalassemia alleles,581casesare β-thalassemia alleles, the prevalence of carries of α-thalassemia gene are12.64%,the prevalence of carries of β-thalassemia gene are4.34%, the--SEAaccounted for6.52%, the CD41-42(CTTT) accouted for1.81%.2.13396cord blood were analysis by capillary electrophoresis, there are1212casesare positive for Hb Bart’s,1179cases are α-thalassemia. Use the genetic diagnosis asthe gold standard, Hb Bart’s as the index, for screening of the Hb Bart’s disease andHb H disease, the sensitivity are100%, for screening of the standard α-thalassemiatype, the sensitivity are97.06%, and for screening of the silenceα-thalassemia type,the sensitivity are49.45%, the specificity are all99.71%.3.13396cord blood were analysis by capillary electrophoresis,in the normal neonate,the median percentage of Hb A are18.00%, in the β-thalassemia newborns, the Hb Aare9.80%, two β-thalassemia intermediate, the Hb A are3.10%and7.10%. By UsingMann-Whitney U-test to compare the percentage of Hb A in the normals and thethalassemia neonates, the value of Hb A was significant differences. 4. By recording the gestational age (29w≤GA<42w) of10898cases newborns, overall,the gestational age were correlated significant with the percentage of Hb A bycalculating the Spearman coefficient. for preterm β-thalassemia newborns, the medianpercentage of Hb A are5.10%, for preterm normals, the Hb A are13.90%, the valueof Hb A are significant differences; for term β-thalassemia newborns, the the medianpercentage of Hb A are10.10%, for preterm normals, the Hb A are18.20%, the valueof Hb A are significant differences.5. Using the ROC curve, for premature newborns, the cut-off value of Hb A are11%,the sensitivity is98.60%, the specificity are94.40%; for the term newborns,use thecut-off value of Hb A are13%, the sensitivity is98.40%, the specificity are76.00%.【Conclusion】1. Use capillary electrophoresis to obtain the Hb Bart’s in the umlilical cord blood canbe screening of α-thalassemia, but it missing for the one globin gene deletion(especially for the-α3.7/αα gene type).2. The capillary electrophoresis is applicable to newborn screening of β-thalassemiaby quantification of Hb A. Considering the gestational age, for the screening of termnewborn, use the cut-off value of Hb A was13%, it has high sensitivity and specificity,and it should be lower for premature newborn for better sensitivity.3. The study confirmed it has a high prevalence of thalassemia in GuangdongProvince.