Genotyping of α-thalassemias by the colorimetric nanogold probes

•Nanogold α-thalassemic probes could differentially diagnose and genotype α-thalassemia 1 and α-thalassemia 2 by naked eye.•Discriminative power of color detection was clearly seen by naked eye.•It is sensitive, specific, accurate and cost effective.•It is field applicable and is a promising thalassemia point of care testing.

BackgroundThe novel colorimetric nanogold probe was created to genotype subgroups of the mostly found α-thalassemias. They are α-thalassemia 1 (SEA and THAI deletion) and α-thalassemia 2 (3.7-kb and 4.2-kb deletion).MethodsThe genotyping was performed by two-steps hybridizations. First step was hybridization of target DNA with the nanogold mixed probes of either α-thalassemia 1 or α-thalassemia 2. No hybridization in both reactions showing blue color indicated absence of abnormal genes causing these α-thalassemias. Positive reaction showing either red or purple color was further analyzed in second hybridization with the nanogold single probe. Positive of α-thalassemia 1 was genotyped with the single probes of both SEA and THAI deletion while those of α-thalassemia 2 were genotyped with both 3.7-kb and 4.2-kb deletion.ResultsGenotypic potency of the nanogold mixed and single probes was evaluated using both known diagnosed and suspected clinical samples. The results by naked eye were consistence with those analyzed by standard agarose gel electrophoresis.ConclusionsPotency of the colorimetric nanogold α-thalassemia probes was accurate, precise, sensitive, specific, simple, cheap and field applicable. Color reaction was simply visualized by naked eye. This development is an example of colorimetric molecular diagnosis which can be applied in any genetic detection.