Endogamous marriage and the prevalence of hemoglobin E in ethnic groups of northern Thailand

OBJECTIVE@#To investigate the impact of the endogamous marriage culture on the prevalence of the hemoglobin E (HbE) recessive variant.@*METHODS@#The prevalence of the hemoglobin E (HbE) recessive variant was determined by dot-blot hybridization in 4 endogamous villages (1 Mlabri and 3 Htin ethnic groups) in comparison with 9 other nearby non-endogamous populations.@*RESULTS@#Although the overall HbE prevalence in the population studied (8.44%, 33/391) was not significantly different from that of the general southeast Asian population, a high prevalence and individuals with homozygous HbE were observed in two villages, the Mlabri from Wiang Sa district and the Htin from Thung Chang district of Nan province (26.3% and 26.9%, respectively). The low HbE allelic frequency noticed in some endogamous populations suggests that not only endogamy but also other evolutionary forces, such as founder effect and HbE/β-thalassemia negative selection may have an effect on the distribution of the HbE trait.@*CONCLUSION@#Our study strongly documents that cultural impact has to be considered in the extensive prevalence studies for genetic disorders in the ethnic groups of northern Thailand.

Endogamous marriage and the prevalence of hemoglobin E in ethnic groups of northern Thailand

Objective To investigate the impact of the endogamous marriage culture on the prevalence of the hemoglobin E (HbE) recessive variant. Methods The prevalence of the hemoglobin E (HbE) recessive variant was determined by dot-blot hybridization in 4 endogamous villages (1 Mlabri and 3 Htin ethnic groups) in comparison with 9 other nearby non-endogamous populations. Results Although the overall HbE prevalence in the population studied (8.44%, 33/391) was not significantly different from that of the general southeast Asian population, a high prevalence and individuals with homozygous HbE were observed in two villages, the Mlabri from Wiang Sa district and the Htin from Thung Chang district of Nan province (26.3% and 26.9%, respectively). The low HbE allelic frequency noticed in some endogamous populations suggests that not only endogamy but also other evolutionary forces, such as founder effect and HbE/β-thalassemia negative selection may have an effect on the distribution of the HbE trait. Conclusion Our study strongly documents that cultural impact has to be considered in the extensive prevalence studies for genetic disorders in the ethnic groups of northern Thailand.

DNA Extraction from Buccal Cells for Determination of Nucleotide Polymorphism at rs 1800497 Position in Dopamine D2 Receptor Gene

Substance use disorder is influenced by complex genetic and environmental factors. Many studies found that genetics may play an important role in the development of alcohol dependence. Twin and family history studies revealed that genetics affect a heritability of alcoholism approximately 50-60%. The neurotransmitter in brain especially dopamine may associate with rewarding system that might increase risk in alcohol dependence. The dopamine D2 receptor gene (DRD2) allelic status may influence on development of alcohol dependence due to the change in number of receptor. This study aimed to demonstrate that buccal cells could be used as an alternative source of DNA for PCR-RFLP based method to determine the allelic status of DRD2. The DNA samples were extracted from buccal cells using proteinase K and 5% chelex solution, then amplified by PCR method with some modification of the primer sequence. The optimization for annealing temperature was performed. Our PCR system using an annealing temperature at 56°C yielded the most specific amplified DNA of approximately 200 ng/μl. The PCR product was digested with TaqI restriction enzyme at 65°C overnight. The digested product was separated in 8.5% polyacrylamide gel elctrophoresis for genotyping.