Hemoglobin variants in Thailand: Data from a referral center at Khon Kaen University in 2015

Abstract

Since the implementation of a prevention and control program of thalassemia in Thailand, a number of Hb analyses and identification of Hb variants in Thai population have been increasingly encountered but most of them cannot be diagnosed in routine setting. Accurate diagnoses of these variants are important for planning of appropriate management and genetic counseling. This requires the study on the hematological and molecular features and frequencies of Hb variants in the population. Study was conducted till June 2015 at CMDL on a large cohort of more than 30,000 unrelated subjects, inhabiting in all geographical parts of Thailand. Among these subjects investigated, 837 were found to Hb variants. Of these 841 subjects, 196 (23.3 %) cases with 15 α-chain variants, 597 (71.0 %) cases with 17 β-chain variants and 48 (5.7 %) cases with four db- or d-chain variants were detected. A total of more than 35 Hb variants including novel ones have been found in Thai population with different frequencies. Hb variants are common and heterogeneous in Thai population. With varieties of thalassemia and hemoglobinopathies in the population, interactions between them leading to complex syndromes are common and render their diagnoses difficult in routine practices. Information on the spectrum, molecular bases, genotype-phenotype correlation and molecular diagnosis should prove useful for management, genetic counseling and further population genetic study of Hb variants.