Diagnostic Tool Delivers Large Scale Genetic Detection

A microarray system has been developed as a high-throughput diagnostic tool for the detection of beta-thalassemia, a genetic disorder that can lead to severe anemia.

The genetic diagnostic tool is based on arrayed primer extension (APEX) technology and had recently been updated and validated for populations with molecular heterogeneity, or diverse ethnic groups.

In collaborative study carried out at the Cyprus Institute of Neurology and Genetics, (Nicosia, Cyprus), 660 DNA samples collected from eight Mediterranean countries were used for standardization; optimization and validation of the microarray devise, the ThalassoChip. The beta-globin gene region was amplified by polymerase chain reaction (PCR), the products were hybridized to the probes after fragmentation, and the APEX reaction followed. The ThalassoChip has the ability to detect 57 beta-globin gene mutations and three single nucleotide polymorphisms (SNPs) in a single test.

The Cypriot team updated the ThalassoChip slides with new and redesigned probes specially prepared for testing the microarray. The chip is able to detect mutations and SNPs at low concentrations of genetic samples, and can show detectable signal with just 0.15 ng of human genomic DNA. The device used for the detection of mutations and polymorphisms during the validation of the chip was the Genorama QuattroImager detector 003 (Genorama Ltd., Tartu, Estonia).

After the standardization process, 160 human genomic DNA samples were run without the investigators knowing the source. All samples were subsequently shown to be concordant with the conventional diagnosis that was made previously. All samples were screened against the 60 mutations and polymorphisms. The authors concluded that the updated version of the ThalassoChip is versatile, robust, cost-effective, and easily adaptable, but most notably can provide comprehensive genetic diagnosis for beta thalassemia and other haemoglobinopathies. The study was published in the December 2010 edition of the journal Clinical Chemistry and Laboratory Medicine.

Beta thalassemia is a blood disorder that reduces the production of hemoglobin. In people with beta thalassemia, low levels of hemoglobin lead to a lack of oxygen in many parts of the body. Affected individuals also have a shortage of red blood cells (anemia), which can cause pale skin, weakness, fatigue, and serious complications. People with beta thalassemia are at an increased risk of developing abnormal blood clots. Beta thalassemia occurs most frequently in people from Mediterranean countries, North Africa, the Middle East, India, Central Asia, and Southeast Asia.

Related Links:
Cyprus Institute of Neurology and Genetics
Genorama Ltd.