Molecular characteristics of α+-thalassemia (3.7 kb deletion) in Southeast Asia: Molecular subtypes, haplotypic heterogeneity, multiple founder effects and laboratory diagnostics.

Abstract

OBJECTIVE:

The 3.7 kb deletion (-α3.7) is the most common form of α+-thalassemia found in multiple populations which can be classified into three subtypes. In order not to mis-identify it, the molecular information within each population is required. We have addressed this in northeast Thai and Laos populations.

METHODS:

Screening for α+-thalassemia was initially done on 1192 adult Thai subjects. In addition, 77 chromosomes of Thai newborns and 26 chromosomes of Laos with -α3.7 α+-thalassemia were also examined. All subjects were screened for -α3.7 α+-thalassemia and subtyped by PCR-RFLP assay. Exact deletion breakpoint of each -α3.7 subtype was determined by DNA sequencing. α-Globin gene haplotypes were determined.

RESULTS:

The proportions of -α3.7 subtypes found in 216 Thai -α3.7 chromosomes were 94.9% for -α3.7I, 4.2% for α3.7II and 0.9% for -α3.7III. All 26 Laos -α3.7 chromosomes were of -α3.7I variety. At least six α-globin gene haplotypes were associated with the -α3.7I α+-thalassemia.

CONCLUSION:

All -α3.7 subtypes were observed among Southeast Asian population. Haplotype analysis indicated a multiple origin of this common disorder in the region. A multiplex PCR assay has been developed for simultaneous detection of all subtypes of -α3.7 α+-thalassemia as well as other α+-thalassemia found in the region including -α4.2 α+-thalassemia, Hb Constant Spring and Hb Paksé.

• Authors: Thanyaornwanya Charoenwijitkul, Kritsada Singha, Goonnapa Fucharoen, Kanokwan Sanchaisuriya, Phuthita Thepphitak, Preawwalee Wintachai, Rossarin Karnpean, Supan Fucharoen
• Journal: Clinical biochemistry (Clin Biochem) Vol. 71 Pg. 31-37 (Sep 2019) ISSN: 1873-2933 [Electronic] United States
• PMID: 31199903 (Publication Type: Journal Article)
• Copyright: Copyright © 2019 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

Topics

• Adult
• Asia, Southeastern
• Clinical Laboratory Techniques
• Female
• Founder Effect
• Haplotypes
• Humans
• Male
• Multiplex Polymerase Chain Reaction
• alpha-Thalassemia (genetics)