Simple DNA Biosensor Delivers Rapid Screening for Southeast Asian α-Thalassemia Deletion

A team of researchers in Thailand has developed a one-step diagnostic test that combines loop-mediated isothermal amplification with a lateral flow dipstick to detect the Southeast Asian deletion, the most common cause of α-thalassemia 1 in the region. The new assay, described in a study published in PLOS One, achieved perfect sensitivity and specificity in a clinical evaluation involving nearly a hundred Thai subjects, and it returns a visible result without the need for expensive laboratory instruments. For countries where thalassemia remains a heavy public health burden, the technology points toward carrier screening that could be performed in ordinary district laboratories rather than centralized molecular facilities.

Thalassemia is an inherited blood disorder in which the body produces insufficient amounts of hemoglobin, the protein that carries oxygen in red blood cells. The α-thalassemias arise from deletions in the genes that encode the α-globin chains of hemoglobin, and the severity of disease depends on how many of the four α-globin genes are lost. When all four are deleted, a condition known as α-thalassemia 1 or Hb Bart’s hydrops fetalis, the fetus cannot survive; affected pregnancies typically end in stillbirth or death shortly after birth, and mothers face serious obstetric complications. Carriers of a single α-thalassemia 1 deletion, by contrast, are usually healthy and often unaware of their genetic status, which is precisely why population screening matters.

The Southeast Asian deletion, abbreviated –SEA, is the dominant α-thalassemia 1 variant in Thailand and across much of Southeast Asia. Because carrier couples who both carry the deletion face a one-in-four risk in each pregnancy of a fetus with hydrops fetalis, identifying carriers before conception or early in pregnancy allows clinicians to offer genetic counseling and prenatal diagnosis. Conventional detection of the deletion relies on techniques such as gap-polymerase chain reaction, which requires thermal cyclers and gel electrophoresis equipment, along with trained personnel and well-equipped laboratories. In rural or resource-limited settings, those requirements create bottlenecks that delay or prevent screening, leaving many carriers unidentified.

The new assay addresses those constraints by pairing two technologies that are individually simple but powerful together. Loop-mediated isothermal amplification, or LAMP, is a nucleic acid amplification method that operates at a single constant temperature, typically between 60 and 65 degrees Celsius, rather than cycling through the repeated heating and cooling steps demanded by conventional PCR. The technique uses a set of four to six primers that recognize six to eight distinct regions of the target DNA sequence, generating large amounts of product rapidly and with high specificity. Because only a heat block or water bath is needed to maintain the reaction temperature, LAMP can be performed with minimal equipment, making it attractive for field and low-resource applications.

Reading the result of a LAMP reaction, however, has traditionally been a weak point. Standard readouts rely on turbidity changes, colorimetric dyes, or gel electrophoresis, each of which carries drawbacks ranging from subjectivity to the need for laboratory infrastructure. The Thai team solved this by adding a lateral flow dipstick, the same paper-strip format familiar from home pregnancy tests. After amplification, the dipstick is dipped into the reaction mixture, and labeled amplification products migrate along the strip to produce a visible line when the target sequence is present. Results appear within five to ten minutes, and the readout is unambiguous enough that laboratory staff need no specialized training in molecular interpretation.

To build the assay, the researchers designed primers specific for the DNA junction created by the –SEA deletion, so that only chromosomes carrying the deletion are amplified. They then evaluated the test on genomic DNA extracted from 96 Thai subjects: 48 confirmed carriers of the α-thalassemia 1 SEA deletion and 48 individuals without the deletion who served as normal controls. The LAMP reaction was run at 61 degrees Celsius for 60 minutes, after which the products were applied directly to the lateral flow dipsticks. The assay correctly identified every positive sample and every negative sample, yielding 100 percent sensitivity and 100 percent specificity across the study cohort.

Analytical testing established the detection limit of the biosensor at 200 picograms of genomic DNA carrying the SEA deletion, a quantity that corresponds to a small number of cell equivalents and comfortably exceeds the amount of DNA typically obtainable from a routine blood sample. Specificity was further probed by testing DNA carrying other α-thalassemia deletion types, including the THAI deletion, another α-thalassemia 1 variant found in the region. No cross-reactivity was observed, meaning the assay reliably distinguishes the SEA deletion from related deletions that produce different clinical and counseling implications. That discrimination is essential in a region where multiple deletion types coexist and misclassification could mislead reproductive decisions.

The practical advantages of the one-step LAMP-LFD format extend beyond accuracy. The entire workflow, from extracted genomic DNA to a visible dipstick result, can be completed in roughly the time of a single morning’s bench work, and the equipment footprint amounts to a constant-temperature heat source and the dipsticks themselves. There is no need for gel preparation, electrophoresis apparatus, ultraviolet transilluminators, or gel documentation systems, all of which are costly to purchase and maintain. For medical laboratory technologists performing genetic carrier screening, the authors note, the kit’s simplicity and minimal equipment requirements make it well suited to routine service in settings where molecular diagnostics have historically been unavailable.

The public health stakes are considerable. Thailand has long classified thalassemia prevention as a national priority, and prevention programs depend on identifying carrier couples so that they can receive counseling and, when appropriate, prenatal or preimplantation genetic diagnosis. A screening test that is fast, cheap, and accurate lowers the barriers to reaching couples in provincial hospitals and community clinics, where most of the population receives care. By enabling earlier identification of –SEA carriers, the biosensor supports the preventive strategies that clinicians use to reduce the incidence of severe thalassemia, including hydrops fetalis, which remains a significant cause of fetal loss in the region.

The study’s authors, led by Ckumdee and colleagues, position the LAMP-LFD DNA biosensor as a practical bridge between sophisticated molecular genetics and everyday laboratory practice. While further validation on larger and more diverse cohorts would be the natural next step before widespread deployment, the reported performance in this initial evaluation, with perfect concordance across 96 samples and a clear limit of detection, suggests the platform is ready for real-world pilot programs. If adopted broadly, the approach could serve as a model for adapting isothermal amplification and lateral flow readouts to other genetic disorders, extending the reach of carrier screening to communities that molecular diagnostics have yet to serve.

Subject of Research: Development of a LAMP-lateral flow dipstick DNA biosensor for detecting the Southeast Asian α-thalassemia 1 deletion

Article Title: Development of loop-mediated isothermal amplification (LAMP) combined with a lateral flow dipstick DNA biosensor for detection of α thalassemia 1 [Southeast Asia (SEA), –SEA deletion]

Article References: Ckumdee, J., Karnjanaopas, S., Songdej, D., Tungbuppha, N., Kaewphinit, T., Wongsuk, T., & Sanyear, C. (2026). Development of loop-mediated isothermal amplification (LAMP) combined with a lateral flow dipstick DNA biosensor for detection of α thalassemia 1 [Southeast Asia (SEA), –SEA deletion]. PLOS One, 21(10), e0360555. https://doi.org/10.1371/journal.pone.0360555

Image Credits: AI Generated

DOI: 10.1371/journal.pone.0360555

Keywords: α-thalassemia, SEA deletion, LAMP, lateral flow dipstick, DNA biosensor, carrier screening, genetic testing, isothermal amplification, Thailand, hemoglobinopathy, molecular diagnostics, genetic counseling