A single-tube multiplex gap-polymerase chain reaction for the detection of eight β-globin gene cluster deletions common in Southeast Asia.

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 β(0)-thal, (δβ)(0)-thal, (G)γ((A)γδβ)(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 β(0)-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 (G)γ((A)γδβ)(0)-thal, the Chinese (G)γ((A)γδβ)(0)-thal, the Asian Indian deletion-inversion (G)γ((A)γδβ)(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.