BACKGROUND DNA piezoelectric biosensors have become a promising tool in molecular medicine since they do not require any label or staining. Here, a DNA piezoelectric biosensor based on a quartz crystal microbalance (QCM) was created to identify abnormal genes causing α-thalassemia 1 (SEA deletion). METHODS The functionalized gold electrode of the quartz crystal was coated with avidin and the biotinylated DNA probe was attached. The target gene causing α-thalassemia 1 was amplified and hybridized with the immobilized probe. DNA hybridization was indicated by changes in the quartz resonance frequencies. Diagnostic ability of the new α-thalassemia 1 biosensor was validated using both known and unknown blood samples. Specificity was tested using samples of β-thalassemia and α-thalassemia 2. Stability of the sensor was also evaluated. RESULTS The new biosensor could clearly identify α-thalassemia 1 (SEA deletion), both carrier and disease states, from the normal genotype. Identification accuracy was compatible to the standard gel electrophoresis. It was specific only to α-thalassemia 1 since no cross reaction was found with β-thalassemia and α-thalassemia 2. The sensor could be kept at room temperature up to 6 months with consistent identification accuracy. CONCLUSIONS The label free QCM based biosensor was successfully developed to diagnose an abnormal human globin gene causing α-thalassemia 1 (SEA deletion). Its accuracy, specificity and sensitivity were comparable to the standard method. Its stable diagnostic potency up to 6 months implied its field application in thalassemic control program.