Molecular Epidemiology of Hemoglobinopathies in Cambodia

Abstract

Determining the magnitude of the thalassemia problem in a country is important for implementing a national prevention and control program. In order to acquire accurate thalassemia prevalence data, the gene frequency of α- and β-thalassemia (α- and β-thal) in different regions of a country should be determined. The molecular basis of thalassemia in Cambodia was performed by polymerase chain reaction (PCR)-based techniques in a community-based cross-sectional survey of 1631 unrelated individuals from three regions, Battambang, Preah Vihear and Phnom Penh. Thalassemia mutations were detected in 62.7% of the three studied population of Cambodia. Hb E (HBB: c.79G > A) was the most common β-globin gene mutation with a frequency ranging from 0.139 to 0.331, while the most frequent α-globin gene mutation was the -α(3.7) (rightward) deletion (0.098-0.255). The other frequencies were 0.001-0.003 for β-thal, 0.008-0.011 for α-thal-1 (- -(SEA)), 0.003-0.008 for α-thal-2 [-α(4.2) (leftward deletion)], 0.021-0.044 for Hb Constant Spring (Hb CS, HBA2: c.427T > C) and 0.009-0.036 for Hb Paksé (HBA2: c.429A > T). A regional specific thalassemia gene frequency was observed. Preah Vihear had the highest prevalence of Hb E (55.9%), α-thal-2 (24.0%) and nondeletional α-thal (15.1%), whereas Phnom Penh had the lowest frequency of thalassemia genes. Interestingly, in Preah Vihear, the frequency of Hb Paksé was extremely high (0.036), almost equivalent to that of Hb CS (0.044). Our results indicate the importance of micromapping and epidemiology studies of thalassemia, which will assist in establishing the national prevention and control program in Cambodia.

Effect of health education on severe thalassemia prevention and control in communities in Cambodia

“…Even though there is a reported high prevalence of thalassemia in Cambodia [ 10 ], we did not encounter many cases of severe thalassemia carriers (α 0 - and β 0 -thalassemia) in the current community-based study. This study’s result was similar to a recent community-based study by Karakochuk et al [ 17 ].…”

“…The common types of thalassemia in Southeast Asia are α 0 -thalassemia, α + -thalassemia, β 0 -thalassemia, hemoglobin (Hb)E, and Hb Constant Spring [ 9 ]. In Cambodia, the respective reported prevalence of α-thalassemia, β-thalassemia, and Hb E is 30–40%, 0.8–1.1%, and 13.9–33.1% [ 10 ].…”

Molecular prevalence of thalassemia and hemoglobinopathies among the Lao Loum Group in the Lao People’s Democratic Republic

“…This α-thalassemia frequency differs from those reported in neighboring South East Asian countries, including Vietnam, Thailand, and Cambodia, which show a higher frequency of the -α 3.7 deletion. 26,27 The severe forms of the disease found in the Lao PDR may be more serious than those found in these neighboring countries. The overall prevalence of β-thalassemia identified in the present work is 2.54%, which is similar to those reported in previous studies and in neighboring Thailand.…”

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

“…In our database for all of Southeast Asia, the number of surveys that tested for all three forms of α-thalassaemia was 40. Amongst these, the overall α-thalassaemia gene frequency ranged from 0% in populations from peninsular Malaysia to 35.4% in Preah Vihar, Cambodia (26). A higher allele frequency of 49% was also reported in the So ethnic group from Khammouane Province in Lao PDR, although the sample size for this study was small ( N = 50) (27).…”

“…α + -thalassaemia, the most prevalent form, reached allele frequencies of 26% in Cambodia (Figure 2B) (26). The surveys revealed a clear north-to-south decline in the distribution of α + -thalassaemia across the region, with a single high allele frequency estimate of 16.8% observed in Sabah in Malaysian Borneo (29).…”