**1.5 Problem of β-thalassemia and HbE**

The carriers of β-thalassemia and HbE do not have clinical burden as they are clinically normal and have normal quality of life. However, if the β-thalassemia carriers get married with the HbE carriers, they will have 25% chance of producing the HbE/β-thalassemia babies. The HbE/β-thalassemia or sometimes called the β-thalassemia/HbE disease is a thalassemia syndrome that presently is known to be clinically heterogeneous [10–12]. Some patients are very mild, while some are very severe. The severe cases always required regular blood transfusion which always ends up with iron overloading condition. Without proper management of this iron overloading, several fatal complications occur, leading to low quality of life and, finally, pre-death at young age.

## **1.6 Diagnosis of β-thalassemia and HbE**

The diagnosis of β-thalassemia and HbE involves both clinical and laboratory investigations. Clinical data can only identify the affected patients, but cannot

definitely identify types of thalassemia the patients are suffering. Laboratory data thus help define specific types of thalassemia disease of those affected individuals. For the carriers, as they are clinically normal, clinical data are of no use. Only laboratory data can define β-thalassemia and HbE carriers.

Conventionally, the laboratory tests for diagnosis of β-thalassemia and HbE include screening tests and confirmatory tests. Initial screening tests are defined as techniques that are simple and relatively low cost, which can indicate the possibility of having thalassemia. These tests should involve the least sample pretreatment and rapid sample preparation and may not need special instrumentation. This would lead to low cost and high sample throughput analysis. The screening tests, however, cannot provide the information on the exact type of thalassemia of the positive persons. Positive samples need further confirmatory test while negative samples can be eliminated from further complicated and expensive testing.

The screening tests for β-thalassemia carriers comprise one-tube osmotic fragility test (OFT) and automated red blood cell indices (mean corpuscular volume; MCV, mean corpuscular hemoglobin; MCH, and red cell distribution width; RDW). Screening tests for HbE carriers are composed of all tests performed to screen for the β-thalassemia carrier plus the specifically established for HbE screen such as dichlorophenolindophenol precipitation (DCIP) test or HbE tube test or HbE test [13–16]. These screening tests, however, cannot provide the information on the exact type of thalassemia of the positive persons.

The purpose and methodologies of confirmatory tests for β-thalassemia and HbE are identical. The confirmatory tests must be highly specific in order to obtain the correct diagnosis of carriers of β-thalassemia and HbE as well as the disease state of HbE/β-thalassemia and homozygote or compound heterozygote of the β-thalassemia gene. The confirmatory tests include;

