Molecular Epidemiology of Hemoglobinopathies in Cambodia

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 alpha- and beta-thalassemia (alpha- and beta-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 beta-globin gene mutation with a frequency ranging from 0.139 to 0.331, while the most frequent alpha-globin gene mutation was the -alpha(3.7) (rightward) deletion (0.098-0.255). The other frequencies were 0.001-0.003 for beta-thal, 0.008-0.011 for alpha-thal-1 (- -(SEA)), 0.003-0.008 for alpha-thal-2 [-alpha(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 Pakse (HBA2: c.429A>T). A regional specific thalassemia gene frequency was observed. Preah Vihear had the highest prevalence of Hb E (55.9%), alpha-thal-2 (24.0%) and nondeletional alpha-thal (15.1%), whereas Phnom Penh had the lowest frequency of thalassemia genes. Interestingly, in Preah Vihear, the frequency of Hb Pakse 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.