Problems in determining thalassemia carrier status in a program for prevention and control of severe thalassemia syndromes: a lesson from Thailand.

BACKGROUND: Prevention and control of severe ß thalassemia by carrier detection and identification of couples at risk in developed countries is one of the most successful stories in modern medicine. Similar programs in developing countries especially Southeast Asia, are more problematic because both α and ß thalassemias are highly prevalent. In Thailand, there are limited data on whether we could determine, based on hematological phenotypes, the mutation severity and/or coinheritance of α thalassemia in ß thalassemia traits. METHODS: Comprehensive molecular, hematology and hemoglobin analyses of the α and ß globin genes were performed in 141 healthy individuals identified as ß thalassemia carriers. RESULTS: Seventeen different ß globin mutations were successfully identified out of all cases analyzed. Although the majority of the mutations identified were the ß° or severe ß⁺ thalassemia alleles, a high proportion of mild mutations (25%) was observed. Of these ß thalassemia traits, 22.3% were found to co-inherit the α thalassemias. Milder hematological phenotypes were noted in ß⁺ compared with ß° thalassemia traits when the α globin genes were intact. Although co-inheritance of α° thalassemia might be suspected in cases with skewed profiles, due to the overlapping values, it remains difficult to apply these parameters for reliable carrier determination. CONCLUSIONS: A combination of hemoglobin analysis and DNA testing seems to be the best way to confirm carrier status in a region with high frequency for both α and ß thalassemias. Underdiagnoses of carrier status could hamper the effectiveness of a thalassemia prevention and control program.

HLA class II (DRB1, DQA1 and DQB1) allele and haplotype frequencies among HIV-infection discordant Thai couples.

We investigated the association of HLA-DRB1, -DQA1 and -DQB1 alleles and haplotypes in 33 Thai HIV discordant couples. A significantly lower frequencies of DRB1*14 (3.0% vs 11.3%, p = 0.048) and DQA1*0103 (0.0% vs 5.63%, p = 0.042) alleles were found in the seropositive individuals when compared with HIV-negative controls. In contrast, there was no significant difference in HLA-DQB1* allele frequencies. The haplotype analysis revealed that DRB1*1501-DQA1*0102-DQB1*0601 (7.6% vs 0.0%, p = 0.002), DRB1*0405-DQA1*0302-DQB1*0401 (7.6% vs 1.3%, p = 0.024) and DRB1*1401-DQA1*0104-DQB1*05031 (6.1% vs 0.0%, p = 0.007) were found to be significantly higher frequencies when compared between HIV seronegative partners and HIV negative controls, but DRB1*1501-DQA1*0102-DQB1*0502 (0.0% vs 8.1%, p = 0.01) was significantly lower. The DRB1*1602-DQA1*0101-DQB1*0502 (4.6% vs 0.0%, p = 0.024) haplotype was found to be significantly higher frequencies in HIV seropositive individuals when compared to HIV negative controls but the DRB1*1502-DQA1*0101-DQB1*0501 (1.5% vs 8.1%, p = 0.049) haplotype was lower.