Characterization of beta globin gene mutations in Zanjan province: An introduction to prenatal diagnosis of Thalassemia

B-thalassemia is an autosomal recessive disease characterized by reduction or complete absence of b-globin gene expression. It has been estimated that more than 2,000,000 carriers as well as 20,000 patients affected with b-thalassemia are living in Iran, a country with more than 70 million population and great ethnic diversity. In this study we aimed to find out the b-globin gene frequency and determine the spectrum of b-globin gene mutations in Zanjan province [northwest region] of Iran. 5527 individuals who were referred for pre-marriage tests to Zanjan clinic as well as 27 thalassemia patients were studied. Altogether one hundred and five chromosomes from 78 unrelated Bthalassemia patients or carriers were examined for b-globin gene mutations by ARMS-PCR and direct gene sequencing. Based on the previous information on common mutations in Mediterranean populations 24 sites were analyzed. It was found that the b-thalassemia frequency is 1.2 for Zanjan region. Using the above techniques, the mutations for 90/105 [86.7] of b-thalassemia chromosomes [13 different mutations] were identified. Fifty eight percent of the mutations were of common .Mediterranean. type. Of which, IVS-I 110 mutation showed the highest frequency [29.5] followed by IVS-II-1 [13.3], IVS-I-1 [12.4] and IVS-I-6 [2.9]. 10.5% of mutations were of common Asian Indian mutations [Fr 8/9, 6.7% and IVS-I-5, 3.8] respectively. CD5 and CD30 and CD36-37 mutations accounted for 13.3% of the mutations. [5.7%, 0.95% and 6.7% respectively] Mutations in 14 chromosomes [13.3] remained uncharacterized. These data suggests that the spectrum of mutations in Zanjan province differs from those reported from other parts of Iran, but Mediterranean type of mutations are more frequent in Zanjan region. Therefore, in order to save the time and cost, it is recommended that for prenatal diagnosis of thalassemia in Zanjan province analysis of Mediterranean mutations should be considered as a front line screening strategy

Transduction of COS-7 and K562 cell lines by recombinant lentiviral particles carrying miniLCR and B-globin gene: Introduction to gene therapy of major B-thalassemia

Beta-thalassemia is caused by absence of reduction of beta-globin chain synthesis. One of the effective therapeutic methods for this disease can be gene therapy by viral vectors. The capacity of lentiviral vectors is approximately 8 kb, we designed a 6 kb construct containing mini LCR and beta-globin gene instead of LCR region. The aim of this study is to make a recombinant lentiviruses containing miniLCR and beta-globin gene for transfer to the target cells for gene therapy of beta-thalassemia. HS2, HS3, HS4 segments [miniLCR] and beta-globin gene with 5' and 3' UTR were amplified from the genomic DNA of a normal individual by PCR. Each segment was cloned in pTZ57R/T vector and then sub cloned first into the pBGGT vector and finally into the pLenti-Dest vector. Final transfer vector and the three helper packaging plasmids [Plp1, Plp2 Plp/VSVG] were contransfected into 293T packaging cells using lipofectamine 2000. Harvested viruses were confirmed by RT-PCR on extracted RNA of these recombinant lentiviruses. The titer of lentiviral stock determined in a K562 cell line and compared with COS-7 cell line. The titer in both cell lines was the same. Optimum MOI for COS-7 cell line was 5 and when polybrene was used transduction increased by 2 fold. The remaining transduced COS-7 colonies were expanded and DNA was extracted. By PCR, random intergration construct into the genome was evaluated. The produced lentiviruses can be an appropriate means for effective transfer of the designed construct into dividing and non-dividing cells such as hematopoetic stem cells for transplantation of beta thalassemia patients. Efficiency of transduction by leniviruses is more than the gene targeting technique. Also units of HS2, HS3 and HS4 regions in mini LCR and selection of larger HS3 unit may increase the expression of beta globin gene

Clinical phenotypes and molecular diagnosis in a hitherto interaction of Hb E/beta thalassemia syndrome (beta(E)/beta(-31), (A -->G)).

Molecular identification of affected alleles in the index family with rare mutation(s) and/or interaction(s) is an important prerequisite toward a proper genetic counseling. In Thailand, where more than 30% of the populations are heterozygotes for either alpha or beta thalassemia mutation(s). More than 60 different thalassemia syndromes resulting from the interactions of these heterogeneous alleles have been observed. The majority of patients in the hospital based-study are compound heterozygotes for beta thalassemia alleles and another hemoglobinopathy namely Hb E, highly prevalent in Thailand, gave rise to Hb E/beta thalassemia syndrome. The phenotypes of these syndromes vary from asymptomatic individual to a very severe phenotype mimic that of beta thalassemia major. In this report, we describe a three-year-old Thai girl presenting with mild hypochromic microcytic anemia since birth. She was born prematurely and developed anemia within the first week of life. The cause of anemia was suspected to result from prematurity and low intrauterine iron storage, however hypochromic anemia did not resolve after a three-month of iron supplement therapy. Subsequent studies indicated that the patient had Hb E/beta thalassemia disease and the molecular study revealed that the patient was a compound heterozygote for Hb E and a rare beta thalassemia mutation (beta(-31), A --> G). This hitherto genotype results in a relatively mild clinical symptom since the patient's baseline Hb values were around 9-10 g/dL with normal weight and height development during the follow-up period.

Genetic variants of beta-globin gene in Thai malaria patients.

Hemoglobin E (E26K variant of beta-globin gene) causing hemoglobinopathy is commonly observed in parts of Thailand, regardless of the hematologic disadvantage of the homozygotes. In order to detect further variants of the beta-globin gene, we performed variation screening for exon 1 of the beta-globin gene in 64 adult patients with P. falciparum malaria, living in northwest Thailand. We identified E26K and two novel variants, 59C>T and IVS+1G>T. IVS+1G>T lies on the splice donor site, and a substitution of A for G at the same site (IVS+1G>A) is known to be linked to beta-thalassemia. Thus, the biological significance of IVS+1G>T and its association with malarial infection should be clarified in future studies.