Molecular Characterization of Hb H and AEBart’s Diseases in Thai Children: Phramongkutklao Hospital Experiences.

BACKGROUND

Alpha-thalassemia is a common genetic disorder in Thailand and is caused by either deletion or non-deletional mutation of one or both α-globin genes. Inactivation of three α-globin genes causes Hb H disease and interaction of Hb H disease with heterozygous Hb E results in AEBart’s disease.

OBJECTIVE

The present study aimed to characterize the genotype of α-globin gene in 81 pediatric patients with Hb H and AEBart’s diseases in Phramongkutklao Hospital, a tertiary care center for thalassemic patients in central Thailand.

MATERIAL AND METHOD

Eighty one unrelated pediatric patients including 60 patients with Hb H disease and 21 patients with AEBart’s disease were enrolled in our study. Mutation analysis was performed by multiplex gap-PCR, multiplex-ARMS and direct DNA sequencing of both HBA1 and HBA2 genes, respectively.

RESULTS

A total of 81 pediatric patients with Hb H and AEBart’s diseases who mainly lived in central Thailand were included in the present study. Eight different α-thalassemia mutations interacting to produce seven genotypes of α-globin gene in both Hb H and AEBart’s diseases were identified. The number of patients in the non-deletional form was higher than in the deletional form for both Hb H (51.6% VS 48.4%) and AEBart’s diseases (52.4% VS 47.6%). The SEA deletion (--SEA) was the most common (98.8%) α-thalassemia 1 mutation. While 3.7-kb deletion (-α3.7) was the most common (90%) α-thalassemia 2 deletion, Hb CS was the most common (90%) non-deletional a-thalassemia 2. Uncommon non-deletional α-thalassemia 2 mutation identified in our study were Hb QS, Hb PS and initiation codon mutation, respectively.

CONCLUSION

All of the α-thalassemia mutation in our pediatric patients with Hb H and AEBart’s diseases have been characterized by the combination of molecular techniques including multiplex gap-PCR, multiplex-ARMS and DNA sequencing of HBA1 and HBA2 genes.