A Single-Tube Multiplex Gap-Polymerase Chain Reaction for the Detection of Eight β-Globin Gene Cluster Deletions Common in Southeast Asia

Abstract

Up to now, more than 200 different β-thalassemia (β-thal) mutations have been characterized. The majority are point mutations causing expression defects. Only approximately 10.0% of the defects are caused by large deletions involving the β-globin gene cluster causing β⁰-thal, (δβ)⁰-thal, ^Gγ(^Aγδβ)⁰-thal and other conditions with or without persistence of fetal hemoglobin (Hb). For the prevention of severe forms of β-thal intermedia and β-thal major, it is important to identify carriers of point mutations as well as carriers of deletions.

β-Thalassemia and related disorders are most commonly present among populations from all Mediterranean countries as well as Southeast Asia, India, Africa, Central America and the Middle East. Twelve relatively frequently occurring deletion types have been described involving the β-globin gene cluster. These include the 105 bp β⁰-thal deletion, the 619 bp deletion, the 3.5 kb deletion, the Southeast Asian (SEA) deletion, the Filipino deletion, Hb Lepore, the Thai (δβ)⁰-thal, the Siriraj J ^Gγ(^Aγδβ)⁰-thal, the Chinese ^Gγ(^Aγδβ)⁰-thal, the Asian Indian deletion-inversion ^Gγ(^Aγδβ)⁰-thal as well as the (hereditary persistence of fetal hemoglobin) HPFH-6 and HPFH-7 deletions.

To improve the rapid detection of the eight common β-globin cluster deletions in Southeast Asian countries, a simple molecular technique based on a single-tube multiplex gap-polymerase chain reaction (PCR) has been developed in this study. This technique provides a fast, simple and cost effective diagnostic test for deletion types of β-thal that can be applied in every molecular diagnostic laboratory having standard PCR equipment.

• Single-tube multiplex gap-polymerase chain reaction (PCR)
• β-Globin cluster deletions
• Southeast Asia
• Screening for β-thalassemia (β-thal)

ACKNOWLEDGMENTS

We thank all the staff at the Department of Human and Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands for participating in this study.

Declaration of Interest

This study was supported by grants from the Office of the Higher Education Commission [the National Research University (NRU) Project, Khon Kaen University, Khon Kaen, Thailand]. J. Tritipsombut was supported by the CHE-PHD-Scholarship program of the Office of the Higher Education Commission, Ministry of Education, Thailand. V. Viprakasit and N. Chalaow were supported by the NRU Grant to Mahidol University, Mahidol, Thailand. The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.