ScienceAsia 12 (1986): 009-021 |doi: 10.2306/scienceasia1513-1874.1986.12.009
MOLECULAR MECHANISMS OF THALASSEMIA IN THAILAND
PRANEE (WINICHAGOON) FUCHAROEN and SUTHAT FUCHAROEN
ABSTRACT: Thalassemia syndrome, resulting from defective synthesis of globin chains, is the most common genetic disorder in Thailand. -Thalassemia 1 occurs from deletion of both of the duplicated -globin genes. -Thalassemia 2 is the result of a deletion leading to loss of one -globin gene, classified either as leftward (4.2 kb) deletion or rightward (3.7 kb) deletion; the latter is more common in Thai patients. Nondeletion -thalassemia, so far, is rare or absent in the Thai population. Studies of -globin gene cluster in -thalassemia using restriction endonuclease DNA polymorphisms reveal 17 different haplotypes. However, 80.3 %of 158 -thalassemia chromosomes analysed show two common haplotypes, + - - - - - +and + - - - - + +. Point mutations and small deletions or insertions in the nucleotide sequences are responsible for the molecular defects of - thalassemia. In contrast to - thalassemias, a wide area of gene deletion involving the A -, - and - globin genes, resulting in (A ) o- thalassemia in two unrelated families, have been identified. Hemoglobin (Hb) E and Hb Constant Spring, the two most common abnormal globin variants, also behave like thalassemia.
Division of Hematology, Department of Medicine, Faculty of Medicine Siriraj Hospital and The Thalassemia Center, Faculty of Graduate Studies, Mahidol University, Bangkok 10700, Thailand.
Received 27 November 1985