Hemoglobin Variants in Northern Thailand: Prevalence, Heterogeneity and Molecular Characteristics.

Abstract

There are limited data on hemoglobin (Hb) variants among peoples of northern Thailand. Hence, we determined the prevalence of Hb variants among a large cohort from this region. A study was done on 23,914 subjects recruited from eight provinces during June 2012-January 2014. Hb was analyzed by high performance liquid chromatography (HPLC) and capillary electrophoresis, and corresponding mutations were identified by polymerase chain reaction. Among 23,914 subjects examined, 211 (0.88%) were found to carry 14 different Hb variants. Five α-globin chain variants were identified: Hb Q-Thailand (n = 40; 19.0%), Hb Hekinan (n = 8, 3.8%), Hb Siam (n = 2, 0.9%), Hb Beijing (n = 1, 0.5%), and Hb Kawachi (n = 1, 0.5%), not previously described in the Thai population. Seven β-globin variants, including Hb Hope, Hb Tak, Hb S, Hb J-Bangkok, Hb G-Makassar, Hb C, and Hb Korle-Bu, were found in 115 (54.5%), 30 (14.2%), 3 (1.4%), 3 (1.4%), 1 (0.5%), 1 (0.5%), and 1 (0.5%) subjects, respectively. The remaining five subjects (2.4%) were carriers of two different δ-globin chain variants. A different spectrum and frequencies of Hb variants were noted compared to other geographical areas. Haplotype analysis demonstrated multiple origins for Hbs Hope and Tak and confirmed a non-African origin of Hb C. Several genetic interactions between these variants with other hemoglobinopathies were encountered. Associated hematological phenotypes and novel Hb derivatives formed were presented. The prevalence and molecular heterogeneities of the Hb variants found in this large cohort of the northern Thai people's should prove useful in developing a screening program, and for the performance of additional population genetics studies of hemoglobinopathy in the region.