Fig 1.
Determination of the lower limit of detection (LOD) of the developed LAMP colorimetric assays for α0-thalassemia (SEA and THAI deletion) and gel electrophoresis.
The DNA template ranges 1.25–40 ng/reaction, including (A) α0-thalassemia (SEA deletion), (B) α0-thalassemia (THAI deletion), and (C) normal. Specificity of the developed LAMP colorimetric assays was demonstrated on subjects with various thalassemia genotypes as indicated for (D) α0-thalassemia (SEA deletion) and (E) α0-thalassemia (THAI deletion).
Table 1.
Protocols of the LAMP colorimetric assays for α0-thalassemia (SEA and THAI deletions), and normal DNA sequence.
Sequences of the oligonucleotide primers used in each protocol and the LAMP reaction mixtures are listed.
Fig 2.
The possible genotypes of the fetus as examined using the LAMP colorimetric assays in prenatal diagnosis of Hb Bart’s hydrops fetalis syndrome (SEA deletion).
A, B, and C represent homozygous α0-thalassemia, heterozygous α0-thalassemia, and normal subject, respectively. S and N indicate the LAMP colorimetric assays for α0-thalassemia (SEA deletion) and normal DNA sequence.
Table 2.
Thalassemia genotypes of 341 subjects with positive (P) and negative (N) in the LAMP colorimetric assays for α0-thalassemia (SEA deletion and THAI deletion).
P & N are positive and negative, respectively. P* indicates false positive result of the LAMP assays.
Table 3.
Prenatal diagnosis of 33 fetuses at risk of having Hb Bart’s hydrops fetalis syndrome caused by homozygous α0-thalassemia using the LAMP colorimetric assay for α0-thalassemia (SEA deletion) in comparison with a routine conventional gap-PCR.
Fig 3.
Comparison of the conventional screening protocol without LAMP colorimetric assay and the proposed screening protocol with LAMP colorimetric assay for α0-thalassemia.
The cost-effectiveness of the two protocols was also determined on the 341 subjects. The PCR analysis of α0-thalassemia is needed for 330 subjects with the conventional screening protocol, whereas only 69 subjects are required for PCR analysis of α0-thalassemia with the proposed protocol. Break down of the 341 subjects in each screening protocol is indicated. DCIP, dichlorophenolindophenol; OF, osmotic fragility; MCV, mean corpuscular volume.