Prenatal Diagnosis of β-Thalassemia/Hb E by Hemoglobin Typing Compared to DNA Analysis

High resolution DNA melting analysis: an application for prenatal control of alpha-thalassemia

OBJECTIVE

To report the use of real-time gap-PCR using SYTO9 with high-resolution melting analysis (HRMA) in prenatal diagnosis of alpha-thalassemia 1.

MATERIALS AND METHODS

Real-time gap-PCR using SYTO9 with HRMA was performed in 33 DNA samples from chorionic villi sampling (8 normal, 16 heterozygous, and 9 homozygous) to determine the alpha-thalassemia 1 gene [normal and Southeast Asia (-SEA) allele].

RESULT

The dissociation curve analysis in normal and - SEA allele gave a peak of T(m) at 91.80 +/- 0.14 degrees C and 88.67 +/- 0.08 degrees C, respectively. Normal genotype and homozygous alpha-thalassemia 1 showed a single peak of T(m) that corresponded to their alleles. The heterozygotes gave both peaks with higher normal peak and smaller - SEA peak. Thirty one samples showed consistent results with the conventional gap-PCR. Two samples with ambiguous results were confirmed to be maternal DNA contamination on real-time quantitative PCR and microsatellite assay. HRMA from both samples showed similar pattern to that of heterozygotes. However, they showed much smaller normal peak compared with the - SEA peak, which is in contrast to those of heterozygotes and can readily be distinguished.

CONCLUSION

HRMA with SYTO9 is feasible for prenatal diagnosis of alpha-thalassemia. It had potential advantage of prompt detection maternal DNA contamination.