The molecular basis of alpha-thalassemia in Thailand.
Southeast Asian J Trop Med Public Health
;
1992 ; 23 Suppl 2(): 7-13
Article
in English
| IMSEAR
| ID: sea-33519
ABSTRACT
Alpha thalassemia is the most common single gene mutation worldwide. In Thailand there exists 15-30% alpha-thalassemia carriers distributed throughout the country. DNA analysis by Southern blot hybridization reveals that the two major alpha-thalassemia alleles, alpha-thalassemia 1 and alpha-thalassemia 2 have different extents of alpha-globin gene deletion. In alpha-thalassemia 1, approximately 20 kb of DNA including the two linked alpha 1-and alpha 2-genes are removed and only the alpha-globin gene is intact. Total deletion of the alpha-globin gene cluster is rarely observed. In contrast, only one alpha-globin gene is deleted in alpha-thalassemia 2 of which two types have been detected, one involving a deletion of 4.2 kb of DNA (leftward type, -alpha 4.2) and another of 3.7 kb (rightward type, -alpha 3.7); the latter being more common than the former in Thailand. Compound heterozygosity for alpha-thalassemia 1 and alpha-thalassemia 2 results in HbH disease while homozygosity for alpha-thalassemia 1 leads to Hb Bart's hydrops fetalis, the most severe form of thalassemic disease. Three alpha-thalassemic hemoglobinopathies have been detected in Thailand, two of which produce a remarkable reduction in gene product. Upon interacting with alpha-thalassemia 1 gene they can lead to HbH disease. The most common in this group is Hb Constant Spring which arises from mutation of the termination codon in the alpha 2-gene resulting in an elongation of the alpha-globin chain.(ABSTRACT TRUNCATED AT 250 WORDS)
Full text:
Available
Index:
IMSEAR (South-East Asia)
Main subject:
Phenotype
/
Prenatal Diagnosis
/
Thailand
/
Blood Protein Electrophoresis
/
Humans
/
Globins
/
Hemoglobin H
/
Hemoglobins, Abnormal
/
Infant, Newborn
/
Hydrops Fetalis
Type of study:
Diagnostic study
/
Screening study
Country/Region as subject:
Asia
Language:
English
Journal:
Southeast Asian J Trop Med Public Health
Year:
1992
Type:
Article
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