Molecular characterization of G6PD mutations reveals the high frequency of G6PD Aures in the Lao Theung population.

BACKGROUND: The prevalence and genotypes of G6PD deficiency vary worldwide, with higher prevalence in malaria endemic areas. The first-time assessment of G6PD deficiency prevalence and molecular characterization of G6PD mutations in the Lao Theung population were performed in this study. METHODS: A total of 252 unrelated Lao Theung participants residing in the Lao People's Democratic Republic (PDR) were recruited. All participant samples were tested for G6PD enzyme activity and G6PD gene mutations. The amplification refractory mutation system (ARMS)-PCR for detecting G6PD Aures was developed. RESULTS: The G6PD mutations were detected in 11.51% (29/252) of the participants. Eight G6PD mutations were detected. The G6PD Aures was the most common mutation identified in this cohort, which represented 58.62% (17/29) of all mutation. The mutation pattern was homogenous, predominantly involving the G6PD Aures mutation (6.75%), followed by 1.19% G6PD Union and 0.79% each G6PD Jammu, G6PD Mahidol and G6PD Kaiping. One subject (0.4%) each carried G6PD Viangchan and G6PD Canton. Interestingly, one case of coinheritance of G6PD Aures and Quing Yan was detected in this cohort. Based on levels of G6PD enzyme activity, the prevalence of G6PD deficiency in the Lao Theung population was 9.13% (23/252). The prevalence of G6PD deficient males and females (activity < 30%) in the Lao Theung population was 6.41% (5/78) and 1.72% (3/174), respectively, and the prevalence of G6PD intermediate (activity 30-70%) was 5.95% (15/252). CONCLUSIONS: The G6PD Aures mutation is highly prevalent in the Lao Theung ethnic group. The common G6PD variants in continental Southeast Asian populations, G6PD Viangchan, Canton, Kaiping, Union and Mahidol, were not prevalent in this ethnic group. The technical simplicity of the developed ARMS-PCR will facilitate the final diagnosis of the G6PD Aures.

Zoonotic Helminthiases in Rodents (Bandicota indica, Bandicota savilei, and Leopoldamys edwardsi) from Vientiane Capital, Lao PDR.

Zoonotic helminths of three rodent species, Bandicota indiaca, Bandicota savilei, and Leopoldamys edwardsi, were investigated in Vientiane capital, Lao PDR. A total of 310 rodents were infected with 11 species of helminth parasites. There were 168 (54.2%) of 310 rodents infected with zoonotic helminths. From our results, there are six recorded zoonotic helminth species, and the highest prevalence was exhibited by Raillietina sp. (30.7%), followed by Hymenolepis diminuta (17.7%), Hymenolepis nana (2.6%), Echinostoma ilocanum (1.9%), Echinostoma malayanum (1.3%), and Angiostrongylus cantonensis (1%). This is the first study of zoonotic helminths in L. edwardsi and the first report of H. diminuta, H. nana, E. ilocanum, and E. malayanum in Bandicota indica and B. savilei, and the first demonstration of A. cantonenensis in B. indica in Lao PDR. From our results, these three rodents are potentially important reservoir hosts of zoonotic helminths. Thus, effective control programs should be considered for implementation to prevent the transmission of these zoonoses in this area.

Thalassemia and hemoglobinopathies in pregnant Lao women: carrier screening, prevalence and molecular basis.

To provide relevant evidence base for implementation of a prevention and control program for thalassemia in the Lao People's Democratic Republic (Lao PDR), we have evaluated a simple screening protocol and examined the prevalence and the molecular basis of thalassemia in pregnant Lao women. The study was conducted on 307 pregnant women attending the Mother and Child Health Hospital, Vientiane. Initial screening was performed locally, applying a combined osmotic fragility (OF) and dichlorophenolindophenol (DCIP) test. Erythrocyte counts were recorded. The remaining blood specimens were transferred to Thailand for further hemoglobin (Hb) and DNA analyses. Subjects were divided into four groups according to the results of the screening tests. Among 307 participants examined, 154 (50.2%) had negative results on both tests (-/-), 58 (18.8%) were positive on the OF test but not the DCIP test (+/-), 22 (7.1%) were negative on the OF test but positive on the DCIP test (-/+), and 73 (23.7%) were positive on both tests (+/+). As many as 25 thalassemia genotypes including various complex syndromes were observed. Three clinically important forms of thalassemia including alpha(o)-, beta-thalassemia, and Hb E were identified in 39 (12.7%), 11 (3.6%), and 93 (30.2%) subjects, respectively. The performance characteristic of the initial screening for these three forms of thalassemia was determined. The sensitivity, specificity, positive, and negative predictive values were found to be 99.2%, 85.5%, 83.0% and 99.4%, respectively. Therefore, thalassemia and hemoglobinopathies are prevalent and heterogeneous among the Lao population. Implementation of a simple carrier screening in pregnancy is practicable in the Lao PDR.

Molecular characterization and origins of Hb Constant Spring and Hb Paksé in Southeast Asian populations.

Hemoglobin Constant Spring (Hb CS) and Hb Paksé, two abnormal Hbs characterized by elongated alpha-globin chains resulting from mutations of the termination codon in the alpha2-globin gene, are the most prevalent nondeletional alpha-thalassemias in Southeast Asia. To determine the origins of these two variants in the region, we have determined alpha-globin gene haplotypes associated with these two variants on 120 Thai, eight Cambodian, and six Laos alleles, and the results were compared with those reported previously for the Chinese and Mediterranean. Five haplotypes were found to be associated with 131 alpha(CS) genes examined, whereas a single haplotype was linked to all the alpha(Paksé) genes in these Southeast Asian populations. All the alpha(CS) haplotypes differed from those of the Mediterranean, but one of them was similar to a Chinese alpha(CS) gene reported previously. It is concluded that there are multiple origins of the alpha(CS) and a single origin of the alpha(Paksé) mutations in Southeast Asia. Hematological findings confirm the mild thalassemia intermedia phenotypes for pure homozygous Hb CS and homozygous Hb CS with Hb E heterozygote and Hb E homozygote. The appearance of Hb CS peak by high-performance liquid chromatography analysis indicates the ability to form a tetrameric Hb molecule between the alpha(CS) and beta(E) chains, leading to a novel derivative with similar characteristics to Hb CS.