Download Screening of α-thalassaemia in newborns by capillary

Screening of α-thalassaemia in newborns by capillary electrophoresis system on
fresh and dried cord blood samples
MUSTAFA Langa MBBS1, HAFIZA Alauddin MBBS, MPATH1, MALISA Mohd Yusoff
Dip MLT2, Raja Zahratul AZMA MBBS, MPATH1, AZLIN Ithnin MBBchBAO,
MPATH1, FARISAH N.R. BSc (HONS)2, Noor HAMIDAH Hussein MBBCh, Dr Med Sc1.
1
Departments of Pathology and 2 Laboratory Diagnostic Services, UKM Medical Centre,
Kuala Lumpur.
Background: Hemoglobin Bart’s may also occur in α thalassaemia carriers (1-15% of total
haemoglobin). This study explored the ability of capillary electrophoresis (CE) method
for screening of α-thalassaemia in newborns by means of quantifying Hb Bart’s level on
fresh and dried cord blood samples. Method: Newborn cord blood samples were subjected
to capillary electrophoresis method by means of two different kits (Neonat kit, using dried
blood spot and the Cord blood kit, using fresh cord blood). α-thalassaemia genotypes
were confirmed by molecular analysis. Results: Six hundred samples were analysed, 32
and 33 showed Hb Bart's peak by Neonat and Cord blood kits respectively. Molecular
analysis confirmed the presence of α-gene deletions in all the positive samples. Of the 32
positive samples by Neonat kit, 23 were αα/– –SEA , four –α3.7/–α3.7, two αα/– α3.7 and
three αα/ααCS. Cord blood kit was able to identify a very low level of Hb Bart in one
additional sample with αα/–α3.7. Molecular analysis on 50 randomly chosen samples with
absence of Hb Bart peak revealed 4/50 and 3/50 false negative results by Neonat and
Cord blood kits respectively, all of which carried a single α-gene deletion. The sensitivity
and specificity of CE in α-thalassaemia carrier states detection were 88.89 % and 100 %
respectively. The range of Hb Bart’s using Neonate Kit and CB Kit were 0.5 – 4.1% and
0.5-7.1% respectively. Conclusion: Capillary electrophoresis using fresh or dried spot
cord blood samples were able to detect newborn α-thalassaemia carrier states with a high
sensitivity and specificity, especially for two α-gene deletions.
Keywords: α-thalassaemia, newborns, capillary electrophoresis, cord blood