Gene Mutation Spectrum among Alpha-Thalassaemia Patients in Northeast Peninsular Malaysia.

(1) Background: Alpha (α)-thalassaemia is a genetic disorder that affects 5% of the world population. Deletional or nondeletional mutations of one or both HBA1 and HBA2 on chromosome 16 will result in reduced production of α-globin chains, a component of haemoglobin (Hb) that is required for the formation of red blood cells (RBCs). This study aimed to determine the prevalence, haematological and molecular characterisations of α-thalassaemia. (2) Method: The parameters were based on full blood count, high-performance liquid chromatography and capillary electrophoresis. The molecular analysis involved gap-polymerase chain reaction (PCR), multiplex amplification refractory mutation system-PCR, multiplex ligation-dependent probe amplification and Sanger sequencing. (3) Results: With a total cohort of 131 patients, the prevalence of α-thalassaemia was 48.9%, leaving the remaining 51.1% with potentially undetected α gene mutations. The following genotypes were detected: -α3.7/αα (15.4%), -α4.2/αα (3.7%), --SEA/αα (7.4%), αCSα/αα (10.3%), αAdanaα/αα (0.7%), αQuong Szeα/αα (1.5%), -α3.7/-α3.7 (0.7%), αCSα/αCSα (0.7%), -α4.2/αCSα (0.7%), -SEA/αCSα (1.5%), -SEA/αQuong Szeα (0.7%), -α3.7/αAdanaα (0.7%), --SEA/-α3.7 (2.2%) and αCSα/αAdanaα (0.7%). Indicators such as Hb (p = 0.022), mean corpuscular volume (p = 0.009), mean corpuscular haemoglobin (p = 0.017), RBC (p = 0.038) and haematocrit (p = 0.058) showed significant changes among patients with deletional mutations, but not between patients with nondeletional mutations. (4) Conclusions: A wide range of haematological parameters was observed among patients, including those with the same genotype. Thus, a combination of molecular technologies and haematological parameters is necessary for the accurate detection of α-globin chain mutations.

Molecular Detection of Alpha Thalassemia: A Review of Prevalent Techniques.

Alpha thalassemia (α-thalassemia) is an autosomal recessive disorder due to the reduction or absence of α globin chain production. Laboratory diagnosis of α-thalassemia requires molecular analysis for the confirmatory diagnosis. A screening test, comprising complete blood count, blood smear and hemoglobin quantification by high performance liquid chromatography and capillary electrophoresis, may not possibly detect all the thalassemia diseases. This review focused on the molecular techniques used to detect α-thalassemia, and the advantages and disadvantages of each technique were highlighted. Multiplex gap-polymerase chain reaction, single-tube multiplex polymerase chain reaction, multiplex ligation-dependent probe amplification, and loop-mediated isothermal amplification were used to detect common deletion of α-thalassemia. Furthermore, the reverse dot blot analysis and a single tube multiplex polymerase chain reaction could detect non-deletion mutation of the α-globin gene. Sanger sequencing is widely used to detect non-deletion mutations of α-thalassemia. Recently, next-generation sequencing was introduced in the diagnosis of both deletion and point mutations of α-thalassemia. Despite the advantages and disadvantages of different techniques, the routine method employed in the laboratory should be based on the facility, expertise, available equipment, and economic conditions.