Capillary electrophoresis combining three-step multiplex polymerase chain reactions for diagnosing α-thalassemia

Umbilical Cord Blood Screening for the Detection of Common Deletional Mutations of α-Thalassemia in Bangladesh

α-Thalassemia (α-thal) is assumed to be very prevalent in Bangladesh. We aimed to assess the prevalence of the disease in the country and provide a model for α-thal newborn screening in Bangladesh. We collected umbilical cord blood (UCB) samples from 413 unrelated newborns in Bangladesh. Demographic information, blood indices, osmotic fragility, serum iron (Fe), and zinc (Zn) levels were evaluated for all the subjects. All subjects underwent a polymerase chain reaction (PCR)-based diagnosis for α-thal status, followed by a multiplex gap-PCR-based identification of the deletion type present. Sixty-seven subjects had at least one α-thal deletion (16.22%). We observed that -α^3.7 (rightward), - -^SEA (Southeast Asian), -α^4.2 (leftward), - -^MED (Mediterranean) and - -^THAI (Thailand) deletions were the most common α-globin deletions present in the country, with the -α^3.7 (n = 37) and - -^SEA (n = 18) being most prevalent. The osmotic fragility test (OFT) could predict the presence of α-thal deletions with over 98.0% sensitivity. Complete UCB count analysis revealed significant differences between healthy subjects and subjects with α-thal deletions. Although the iron level was almost the same (108.0 vs. 105.7 µg/dL), a reduced level of Zn (98.6 vs. 71.8 µg/dL, p < 0.01) was observed in the cord blood-derived serum of the subjects with α-thal deletions. Moreover, parental age at the time of delivery, gestational period, and birth weight was lower in the subjects with α-thal deletions. This study provides partial information on the epidemiology of α-thal in Bangladesh and describes a model for α-thal newborn screening in the country.

Rapid identification of the copy number of α-globin genes by capillary electrophoresis analysis

OBJECTIVES

The current study aimed at the rapid identification of the copy number of α-globin genes for the diagnosis of α-thalassemia.

DESIGN AND METHODS

To identify the copy number of α-globin genes in α-thalassemia, we developed a novel method using a multiplex polymerase chain reaction (PCR) in combination with the CE analysis.

RESULTS

The proposed method provides a rapid detection of the common α-globin gene deletions. Sixty-six patients with α-thalassemia and 46 normal controls were included in the present study. The obtained results showed good correlation with those obtained by gap PCR. Moreover, a low amount of maternal cell contamination in the fetus specimen for the prenatal diagnosis of hemoglobin Barts hydrops fetalis as well as the rare multiplicated α-globin genes can be identified using this method.

CONCLUSION

This method provides a convenient and efficient tool for the rapid identification of the copy number of α-globin genes in α-thalassemia and the individuals with α-globin gene multiplication.