Development and validation of a zeta-globin-specific ELISA for carrier screening of the (--SEA) alpha thalassaemia deletion.
OBJECTIVE
The Southeast Asian (SEA) deletion (--(SEA)) represents the most common determinant causing alpha thalassaemia in Southeast Asian countries. The embryonic zeta-globin chain has been defined as a marker for the detection of this deletion in adults. The aim of this study was to develop an appropriate low-cost ELISA for zeta-globin chain detection as a routine screening test for (--(SEA)) alpha thalassaemia deletion.


METHODS
A sandwich ELISA system for zeta-globin chains was established with a pair of zeta-globin-specific monoclonal antibodies prepared in-house, and locally made products. Against a gap-PCR method that was taken as the standard, this assay was validated in a cohort study testing a total of 526 individuals comprising patients scheduled for haemoglobinopathy diagnostic analysis and normal individuals. Routine screening of the (--(SEA)) deletion in 300 random student volunteers was conducted using the assay.


RESULTS
While the cut-off point was set at a percentage positive value of 30, the sensitivity and specificity of this ELISA method were 100% and 99.24%, respectively. The mean intra-assay and inter-assay coefficients of variation among the different concentrations in the optimised ELISA conditions were 2.1-11.4% and 4.3-13.2%, respectively. Seventeen of the 300 volunteers sampled were determined by the ELISA to have the (--(SEA)) deletion; these results were in 100% agreement with the gap-PCR results.


CONCLUSIONS
This study validates the ELISA method described here as a simple, rapid and cost-effective assay that is potentially adaptable for application in large-scale population screening for this prevalent disorder in SEA areas such as southern China.
Tang
L
L
Department of Immunology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China.
Zhu
P
P
Zhou
W J
WJ
Zheng
J
J
Zhou
Y Q
YQ
Fu
N
N
Xu
X M
XM
D000328:Adult; D000911:Antibodies, Monoclonal / Q000276:immunology; D015415:Biomarkers / Q000097:blood; D002648:Child; D002675:Child, Preschool; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D017353:Gene Deletion; D006580:Genetic Carrier Screening / Q000379:methods*; D005820:Genetic Testing / Q000379:methods*; D006801:Humans; D007223:Infant; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult; D017085:alpha-Thalassemia / Q000097:blood / Q000175:diagnosis* / Q000235:genetics; D055543:zeta-Globins / Q000032:analysis* / Q000276:immunology
D000911:Antibodies, Monoclonal; D015415:Biomarkers; D055543:zeta-Globins