Haemoglobin Constant Spring has an unstable α chain messenger RNA

Haemoglobin Constant Spring (Hb CS) is a variant with an elongated α-chain associated with an α⁺ thalassaemia phenotype. The amount of α mRNA relative to β mRNA in reticulocytes was reduced in carriers of Hb CS by an amount equivalent to the reduction observed in carriers of α⁺ thalassaemia. In a patient with Hb CS-H disease there was greater α/β mRNA ratio in bone marrow nuclear RNA than in the peripheral blood. Furthermore, all the α mRNA in the patient's peripheral blood was derived from the α1 (α^A) gene. The data suggest that α^CS mRNA is unstable and degraded in the cytoplasm. This instability may be due to destabilization of a specific sequence in the 3'non-coding region during translation.     

Realistic Food-Based Approaches Alone May Not Ensure Dietary Adequacy for Women and Young Children in South-East Asia

Objectives Micronutrient deficiencies, in southeast Asia (SE Asia), remain a public health challenge. We evaluated whether promoting the consumption of locally available nutritious foods, which is a low-risk micronutrient intervention, alone can ensure dietary adequacy, for women of reproductive age and 6–23 m old children. Methods Representative dietary data from Cambodia, Indonesia, Lao PDR, Thailand and Vietnam were analysed using linear programming analysis to identify nutrients that are likely low in personal food environments (problem nutrients), and to formulate food-based recommendations (FBRs) for three to six target populations per country. Results The number of problem nutrients ranged from zero for 12–23 m olds in Indonesia, Thailand and Vietnam to six for pregnant women in Cambodia. The FBRs selected for each target population, if adopted, would ensure a low percentage of the population was at risk of inadequate intakes for five to ten micronutrients, depending on the country and target population. Of the 11 micronutrients modelled, requirements for iron, calcium and folate were most difficult to meet (≥ 10 of the 24 target populations), using FBRs alone. The number of individual FBRs selected per set, for each target population, ranged from three to eight; and often included meat, fish or eggs, liver/organ meats, vegetables and fruits. Conclusions for practice Intervention strategies need to increase access to nutritious foods, including products fortified with micronutrients, in SE Asia, when aiming to ensure dietary adequacy for most individuals in the population.

     

Nutrition education in Southeast Sulawesi Province,Indonesia: A cluster randomized controlled study

This study evaluated the impact of a nutrition education intervention on child feeding practices and children's nutritional status. Using a randomized controlled trial, we conducted an intervention for 6 months among caregivers with children aged 6–17 months in two subdistricts of Kendari, SE Sulawesi Province, Indonesia. In all, 22 integrated health posts were randomly assigned to an educational intervention or control group with 266 participants in both groups. Participants in the intervention group attended four nutrition classes and received a monthly home visit by cadres (community volunteers), whereas participants in the control group only received standard monthly health care at the health post. The primary study outcome was children's dietary diversity scores (DDSs). Mixed model analysis was conducted to examine the intervention effects on DDS and children's growth adjusting for clustering within subvillages. The study showed the educational intervention had a significant effect on children's DDS. Children in the intervention group had a larger DDS compared with children in the control group (Beta [mean difference] = 0.34, 95% CI: 0.02 to 0.66, P = 0.038). The intervention effect on height‐for‐age z‐score (HAZ) could not be shown (Beta = 0.24, 95% CI: ?0.06 to 0.56, P = 0.112). However, stunting prevalence remained stable in the intervention group but increased in the control group. These results indicated nutrition education delivered through nutrition classes combined with regular home visits by cadres as influencers provided a great potential to be adopted to complement other nutrition programmes in community health centres.     

Thalassemia and abnormal hemoglobin

Thalassemia and abnormal hemoglobins are common genetic disorders in Asia. Thalassemia is not only an important public health problem but also a socio-economic problem of many countries in the region. The approach to deal with the thalassemic problem is to prevent and control birth of new cases. This requires an accurate identification of the couple at high risk for thalassemia. However, the diagnosis of thalassemia carrier states need several tests which are not practical for screening the population at large. Recently we have used two simple laboratory tests to screen for potential thalassemia carriers and hemoglobin E individuals. There is also a new development in using the automatic HPLC to diagnose thalassemic diseases and the carriers. This system gives both qualitative and quantitative analysis of hemoglobin components in the same run with good precision and reproducibility. The system has been applied to study thalassemia and abnormal Hb in adult and cord blood. This system has enabled us to do both prenatal and postnatal diagnosis of thalassemia within the few minutes. However, none of these screening tests can accurately give specific diagnosis of the thalassemia genotype. Specific thalassemia mutation can be carried out by DNA analysis. Many DNA techniques have been used for point mutation detection and small deletion. For the last few years there is a development of DNA chip technology that has been applied for thalassemia mutation as well. Clinically, thalassemia is very heterogeneous in the manifestation. In spite of seemingly identical genotypes, severity of beta thalassemic patients can vary greatly. Heterogeneity in the clinical manifestation of beta thalassemic diseases may occur from the nature of beta globin gene mutation, alpha thalassemia gene interaction and difference in the amount of Hb F production which is partly associated with a specific beta globin haplotype. However, there is still some beta thalassemia cases that have a mild clinical symptom without those known genetic fators interaction suggesting that there are other additional factors responsible for the mildness of the disease.     

Genetic factors affecting clinical severity in beta-thalassemia syndromes

PURPOSE: Heterogeneity in the clinical manifestation of beta-thalassemic diseases may occur from the nature of beta-globin gene mutations, alpha-thalassemia gene interaction, or differences in the amount of hemoglobin (Hb) F production. This study was conducted to determine whether these genetic determinant factors can predict phenotypic severity of patients with beta-thalassemia and to assess the relationship between the genotype and phenotype of the disease. MATERIALS AND METHODS: A total of 144 patients with beta-thalassemia were divided into mild (46 patients), intermediate (55 patients), and severe groups (43 patients). DNA analysis based on polymerase chain reaction technique was performed to characterize types of beta-thalassemia mutation, interaction of alpha-thalassemia, and XmnI polymorphism 5' to Ggamma-globin gene. RESULTS: Two alleles of mild beta-thalassemia mutation (beta+/beta+-thalassemia or beta+-thalassemia/Hb E) resulted in a mild clinical symptom whereas two alleles of severe beta-thalassemia mutation (betao/betao) produced a severe clinical phenotype. Compound heterozygosity for mild and severe alleles of beta-thalassemia (betao/ beta+-thalassemia or betao-thalassemia/Hb E) led to variable severity of anemia. Coinheritance of alpha-thalassemia alleviated the severity of beta-thalassemia disease in those patients with at least one allele of the mild beta-thalassemia genotype. DNA polymorphism at position-158 nt 5' to the Ggamma-globin gene was demonstrated by XmnI restriction enzyme. Homozygote of the XmnI site, +/+, was found to have a strong linkage with high Hb F levels and high hemoglobin production in two patients who had mild clinical symptoms. However, some patients who had XmnI site -/- also had mild clinical symptoms because the XmnI- was found to be associated with beta+-thalassemia mutation. CONCLUSION: Types of beta-thalassemia mutation and coinheritance of alpha-thalassemia in the patient who has at least one allele of the mild beta-thalassemia genotype are predictive for the clinical severity of the disease. However, a mild clinical symptom in some patients with betao/beta+-thalassemia or betao-thalassemia/Hb E who do not have a detectable alpha-thalassemia haplotype and no linkage with XmnI++ suggests that there are other confounding factors responsible for the severity differences of the disease.     

Different molecular defects of G gamma (A gamma delta beta)o-thalassaemia in Thailand

DNA from members of 2 Thai families with conditions considered to be delta beta-thalassaemia were studied by using restriction endonuclease DNA mapping. The propositus in family A is a double heterozygote for beta-thalassaemia and delta beta-thalassaemia. DNA analysis reveals a deletion of the beta-globin gene cluster starting at the area between the Sac I and Eco RI sites near the 3' end of the G gamma-gene and extending through the A gamma-, delta- and beta-genes to an unknown extent downstream. In family B, the propositus is delta beta-thalassaemia/Hb E. Deletion of the beta-globin gene cluster begins in the large intervening sequence of the A gamma-gene and removes both delta- and beta-genes downstream.     

A multi-center study in order to further define the molecular basis of beta-thalassemia in Thailand, Pakistan, Sri Lanka, Mauritius, Syria, and India, and to develop a simple molecular diagnostic strategy by amplification refractory mutation system-polymerase chain reaction.

The spectrum of the beta-thalassemia mutations of Thailand, Pakistan, India, Sri Lanka, Mauritius and Syria has been further characterized by a multi-center study of 1,235 transfusion-dependent patients, and the mutations discovered used to assess the fidelity of a simple diagnostic strategy. A total of 44 beta-thalassemia mutations were identified either by allele-specific oligonucleotide hybridization, amplification with allele-specific primers, or DNA sequencing of amplified product. The results confirm and extend earlier findings for Thailand, Pakistan, India, Mauritius and Syria. This is the first detailed report of the spectrum of mutations for Sri Lanka. Two novel mutations were identified, codon 55 (-A) and IVS-I-129 (A-->C), both found in Sri Lankan patients. Two beta-thalassemia mutations were found to coexist in one beta-globin gene: Sri Lankan patients homozygous for the beta0 codon 16 (-C) frameshift were also homozygous for the beta+ codon 10 (C-->A) mutation. Studies of Sri Lankan, Pakistani, and Indian carriers suggest the codon 10 (C-->A) mutation is just a rare polymorphism on an ancestral allele, on which the beta0 codon 16 (-C) mutation has arisen. Each country was found to have only a few common mutations accounting for 70% or more of the beta-thalassemia alleles. A panel of primers to diagnose the majority of the mutations by the amplification refractory mutation system was developed, enabling a simple molecular diagnostic strategy to be introduced for each country participating in the multi-center study.     

Hemoglobin constant spring in Bangkok: molecular screening by selective enzymatic amplification of the alpha 2-globin gene.

Hemoglobin Constant Spring (Hb CS) is a hemoglobin variant with an elongated alpha-globin chain secondary to a chain termination mutation. The diagnosis of HbCS by electrophoresis is difficult because it is present in very low amounts in the red cells of heterozygotes. Selective enzymatic amplification of the alpha 2-globin gene and allele-specific hybridization for Hb CS gene provided accurate diagnosis of Hb Constant Spring. We have used this approach to detect the alpha cs mutation in the cord blood that contained all four alpha-globin genes but had Hb Bart on electrophoresis. The alpha cs mutation was found in six subjects whose Hb Bart levels were 3.0, 3.2, 3.7, 4.0, 4.9, and 9.8%. The latter also had -alpha mutation on the other chromosome, giving rise to the genotype alpha cs alpha/-alpha, which produced high Hb Bart. The gene frequency for alpha cs in the Thai calculated from a total of 406 cord blood studied in Bangkok was found to be approximately 0.008.     

Molecular screening of the Hbs Constant Spring (codon 142, TAA>CAA, α2) and Paksé (codon 142, TAA>TAT, α2) mutations in Thailand

Hb Constant Spring [Hb CS, α142(H19)Term] and Hb Paksé [α142(H19)Term] occur from the mutation in the termination codon of the α2-globin gene, TAA>CAA (→Gln) and TAA>TAT (→Tyr), respectively. They are the most common nondeletional α-thalassemia (α-thal) variants causing Hb H disease in Southeast Asia. In this study, 587 cord blood samples were screened for the Hb CS and Hb Paksé mutations by a dot-blot hybridization technique using oligonucleotide probes specific for each mutation. The results showed that the prevalence of Hb CS and Hb Paksé in Central Thailand are 5.80 and 0.51%, respectively, which is in concordance with the results from previous studies.     

Multicenter study of the molecular basis of thalassemia intermedia in different ethnic populations

We studied 325 thalassemia intermedia patients from Iran, India, Pakistan, Thailand, Mauritius and Cyprus to examine factors which influence the phenotype. The beta-thalassemia (thal) mutations were determined for 219 beta-thal/beta-thal and 106 beta-thal/Hb E [beta26(B8)Glu-->Lys, GAG-->AAG] thalassemia intermedia patients. Thirty-one different mutations were identified, and their combination gave rise to more than 44 different genotypes, of which 14 (31.8%) had the beta(0)/beta(0), 21 (47.7%) the beta(0)/beta(+) and nine (20.5%) the beta(+)/beta(+) types. Thus, the beta(+)-thal mutations were present in 68.2% of patients. alpha-Thalassemia mutations were present in frequencies higher than in the general population of all ethnic groups studied, as 45% of the patients carried alpha-thal mutations. Correlation of alpha-thal mutations with beta-globin mutations showed that the alpha-thal mutations were mainly co-inherited with the beta(+)-thal mutations. The XmnI (G)gamma polymorphic site at -158 (C-->T) was positive (T) in nine (8.8%) of 102 patients of the beta(+)/beta(+) genotype, and the percentage of both XmnI (G)gamma polymorphism [+/-] (T/C) and [+/+] (T/T) genotypes increased to 42.9 and 87.3, respectively, in the beta(0)/beta(+) and beta(0)/beta(0) patients. This polymorphism was found in the majority of beta(+)-thal/Hb E compound heterozygote patients (88.6%), and beta(0)-thal/Hb E patients (84.8%), suggesting that it could be linked to the Hb E chromosome. Therefore, the XmnI (G)gamma polymorphism at -158 (C-->T) was associated with beta(0)-thal mutations as well as the Hb E chromosome. The present study demonstrates that in cases of thalassemia intermedia with beta(+) mutations, the common ameliorating factor is the presence of alpha-thal mutations, while in cases with beta(0) mutations, the common ameliorating factor is the presence of the XmnI (G)gamma polymorphism at -158 (C-->T).