A comprehensive ethnic-based analysis of alpha thalassaemia allelle frequency in northern Thailand

Abstract

Alpha (α)-thalassaemia is one of the most prevalent hereditary blood disorders, commonly affecting Southeast Asian people, with the highest incidence (30–40%) being seen in northern Thailand. However, this high incidence was estimated without consideration of the variations between ethnic populations and the geographical location of the populations. To address this issue, a total of 688 samples from 13 different northern Thai ethnic groups (30 villages) categorized into three linguistic groups were genotyped for deletional alpha-thalassaemia (-α3.7, -α4.2, --SEA and --THAI) and/or non-deletional alpha-thalassaemia (αCS and αPS) via multiplex gap-PCR and dot-blot hybridization, respectively. Alpha+(-α3.7, -α4.2, αCS and αPS) and alpha°-thalassaemia (--SEA and --THAI) allele frequencies (with 95% Confidence Interval) were the highest in the Sino-Tibetan group [0.13 (0.08–0.18)] and the Tai-Kadai group [0.03 (0.02–0.05)], respectively. With regards to ethnicity, the varying allele frequency of α+ and α°-thalassaemia amongst a variety of ethnic groups was observed. The highest α+-thalassaemia allele frequency was found in the Paluang [0.21 (0.10–0.37)] while α°-thalassaemia allele frequency was the highest in the Yuan [0.04 (0.01–0.10)]. These detailed results of alpha thalassaemia allele frequency and genetic diversity amongst the northern Thai ethnic groups demonstrate the need for ethnicity based thalassaemia prevention programs.

Prevalence of Alpha(α)-Thalassemia in Southeast Asia (2010–2020): A Meta-Analysis Involving 83,674 Subjects

“…This leads to the manifestation of clinical conditions known as α- or β-thalassemia. The most common genetic defect in α-thalassemia is a deletion in the α-globin gene involving one or both globin genes such as -α 3.7 , -α 4.2 , -- SEA , -- THAI , -α CD59 , -α 20.5 , -α IVS I-1 and others ( Figure 1 ) [ 4 , 5 , 6 ]. A highly severe form of deletional α-thalassemia, known as Haemoglobin (Hb) Bart’s hydrops fetalis, is a homozygous α 0 -thalassemia deletion with a complete loss of functional α-globin that leads to foetal death or death shortly after birth.…”

“…Several countries in the Southeast Asia region have reported the prevalence of α-thalassemia in different ethnic groups independently, revealing that the prevalence of α-thalassemia differs from country to country with different ethnicities [ 4 , 5 , 17 , 18 ]. However, no studies have systematically meta-analyzed the prevalence and epidemiology of α-thalassemia—where the results of these similar studies are quantitatively combined—for this region.…”

Anemia and Iron Deficiency Anemia in High School Girls in Nakhon Si Thammarat, Thailand

“…In addition, thalassemia was found to be a highly prevalent cause of anemia in the northeast and Laos. [16][17][18][19] Insufficient iron intake and blood loss were reported as the factors leading to iron deficiency. 5,6,20 This study showed that iron intake from food did not differ among the groups with IDA and others.…”

Estimating the burden of α-thalassaemia in Thailand using a comprehensive prevalence database for Southeast Asia

“…Extensive variation in allele frequencies between different ethnic groups has been observed (36). Due to the nature of this study, and the smoothing of allele frequencies over a continuous spatial domain, our predicted allele frequencies might not fully reflect heterogeneity between local ethnic populations.…”