Hb E-ß-Thalassemia in Five Indian States.

Hb E [ß26(B8)Glu→Lys; HBB: c.79G > A]-ß-thalassemia (ß-thal) has an extremely variable clinical presentation. We report the clinical features of these patients from five Indian states together with their hematological and molecular characteristics. Seventy-eight Hb E-ß-thal patients from different regions [West Bengal (30), Maharashtra (21), Uttar Pradesh (13), Bihar (11), Orissa (3)] were clinically evaluated along with hematological profiles and molecular characteristics (ß-thal mutations, XmnI polymorphisms, α genotypes). Twenty-nine of the 78 patients had a mild clinical presentation (clinical score 2.2 ± 1.1), while 15 had moderate severity (clinical score 6.1 ± 1.2) with occasional transfusion needs, and 34 patients were severely affected (clinical score 8.2 ± 0.5) requiring regular blood transfusions. The age at clinical presentation in the severely affected patients was lower (6 months-10 years) as compared to those with milder symptoms (2 years-34 years). Thirty-four patients showed splenomegaly (spleen ≥3 cm below the costal margin) and five patients were splenectomized. The severe ß+ IVS1-5 (G > C) (HBB: c.92 + 5G > C) was the most common ß-thal mutation, while seven other mutations were also seen. The XmnI [+/+] and [-/-] polymorphisms were seen in 24.1 and 10.3% of mildly affected patients and 14.7 and 17.6% of severely affected patients respectively. A single α gene deletion (-α3.7/αα) was found in 20.7% of mildly affected and 5.9% of severely affected patients, respectively. No specific differences in the clinical, hematological or molecular characteristics were observed in the Hb E-ß-thal patients from various geographic regions or different ethnic groups.

Effect of a group of genetic markers around the 5' regulatory regions of the ß globin gene cluster linked to high HbF on the clinical severity of ß thalassemia.

The clinical and hematological course of ß thalassemia intermedia is influenced by a number of genetic factors which play a role in increasing fetal haemoglobin levels. Several polymorphisms located in the promoters of ß and γ globin gene are involved in influencing the disease severity. Our objective was to study the effect of cis-DNA haplotypes, motifs, or polymorphisms (Pre G γ globin gene haplotypes, Aγ-δ intergenic region haplotypes XmnI and (AT)(x)(T)(y) polymorphisms, ß-LCR HS2 and HS3 site motifs) that may contribute to higher HbF levels and a milder clinical course. We found that a combination of T haplotype of the Aγ-δ intergenic region, TAG Pre-Gγ haplotype, presence of the XmnI polymorphism along with the (AT)(9)(T)(5) motif constitutes a topography that co-relates with raised HbF levels which may contribute in ameliorating the disease severity.

Role of co-inherited Gilbert syndrome on hyperbilirubinemia in Indian beta thalassemia patients.

BACKGROUND: Gilbert syndrome is characterized by mild unconjugated hyperbilirubinemia. The high levels of bilirubin could be related to the co-inheritance of Gilbert syndrome determined either by mutations of the coding region or by variation in the (TA)n motifs of the promoter region of the bilirubin UGT1A1 gene. The co-inheritance of Gilbert syndrome has been reported to elevate bilirubin levels in beta thalassemia and sickle cell disease patients. Aim In this study, we have tried to investigate whether the variability in serum bilirubin levels found in transfusion-dependent beta thalassemia, beta thalassemia intermedia, and heterozygous beta thalassemia individuals could be related to the coexistence of Gilbert syndrome. METHODS: The promoter region (TA)n motifs of the bilirubin UGT1A1 gene were analyzed in 104 beta thalassemia individuals. The control group consisted of 50 healthy individuals. RESULTS: The analysis of the UGT1A1 promoter showed three (TA) motifs: (TA)5, (TA)6, and (TA)7. The frequency of genotype (TA)7/(TA)7 did not differ significantly between the groups studied. A significant difference was observed in mean serum bilirubin levels between individuals showing (TA)7/(TA)7 and (TA)6/(TA)6 genotypes and also between (TA)7/(TA)7 and (TA)6/(TA)7 genotypes among all groups studied. According to the beta genotype, no differences were observed between mean serum bilirubin levels in the three groups (ß(+)/ß(+), ß(0)/ß(+), and ß(0)/ß(0)). CONCLUSION: These results indicate that the (TA)7/(TA)7 configuration is one of the factors responsible for hyperbilirubinemia and, therefore, seems to interfere with the clinical expression of homozygous beta thalassemia. This emphasizes the role played by co-inherited modifying genes on clinical heterogeneity of monogenic disorders.

Clinical and hematological presentation among Indian patients with common hemoglobin variants.

BACKGROUND: Co-inheritance of structural hemoglobin variants like HbS, HbD(Punjab) and HbE can lead to a variable clinical presentation and only few cases have been described so far in the Indian population. METHODS: We present the varied clinical and hematological presentation of 22 cases (HbSD(Punjab) disease-15, HbSE disease-4, HbD(Punjab)E disease-3) referred to us for diagnosis. RESULTS: Two of the 15 HbSD(Punjab) disease patients had moderate crisis, one presented with mild hemolytic anemia; however, the other 12 patients had a severe clinical presentation with frequent blood transfusion requirements, vaso occlusive crisis, avascular necrosis of the femur and febrile illness. The 4 HbSE disease patients had a mild to moderate presentation. Two of the 3 HbD(Punjab)E patients were asymptomatic with one patient's sibling having a mild presentation. The hemoglobin levels of the HbSD(Punjab) disease patients ranged from 2.3 to 8.5 g/dl and MCV from 76.3 to 111.6 fl. The hemoglobin levels of the HbD(Punjab)E and HbSE patients ranged from 10.8 to 11.9 and 9.8 to 10.0 g/dl whereas MCV ranged from 67.1 to 78.2 and 74.5 to 76.0 fl respectively. CONCLUSIONS: HbSD(Punjab) disease patients should be identified during newborn screening programmes and managed in a way similar to sickle cell disease. Couple at risk of having HbSD(Punjab) disease children may be given the option of prenatal diagnosis in subsequent pregnancies.

Effect of Cis Acting Potential Regulators in the ß Globin Gene Cluster on the Production of HbF in Thalassemia Patients.

The clinical presentation of ß-thalassemia intermedia phenotypes are influenced by many factors. The persistence of fetal hemoglobin and several polymorphisms located in the promoters of γ- and ß-globin genes are some of them. The aim of this study was to evaluate the combined effect of the -158 Gγ (C→T) polymorphism and of the (AT)x(T)y configuration, as well as their eventual association with elevated levels of HbF in ß-thalassemia carriers, ß-thalassemia intermedia, ß-thalassemia major and normal controls of Indian origin. The -158 Gγ T allele was found to be associated with increased levels of HbF in ß thalassemia carriers, and not in wild-type subjects. In the homozygous group, the -158 Gγ T allele was significantly higher in the thalassemia intermedia group (66%) as against the thalassemia major group (21%). The (AT)9(T)5 allele did not show any association with raised HbF levels. However 24% of milder cases showed presence of this allele. This study suggests that two regions of the ß globin cluster, whether in cis or in trans to each other, can interact to enhance HbF expression when a ß thalassemic determinant is present in heterozygosity and help in amelioration of the severity of the disease in homozygotes.