Clinical and molecular characterization of β(S) and (G)γ((A)γδβ)⁰-thalassemia in eastern India

Spectrum of hemoglobin disorders in southern Odisha, India: a hospital based study

Background:

Hemoglobin disorders are the leading health concern in the world including India. There is a paucity of literature on the spectrum of hemoglobin disorders in southern districts of Odisha state. This study was undertaken to elucidate the occurrence of different hemoglobin disorders in a tertiary health care facility of Odisha state, India.

Methods:

The study cases were suspected patients of all age groups advised for screening of different hemoglobin disorders. Hemoglobin disorders were screened by sickling slide test and high-performance liquid chromatography (HPLC) using the Variant-II hemoglobin testing system as per the manufacturer's guidelines.

Results:

Over 2 years, 2332 blood samples (including 1102 pediatric and 1230 adult cases) were investigated, out of which, 1380 (59.2%) of cases had abnormal hemoglobin disorders. The most common was sickle cell disorders (48.67%, 1135/2332) followed by β-thalassemia (11.32%, 264/2332). Some rare variants were detected as hemoglobin D^-Punjab, hemoglobin E, hemoglobin Lepore, hereditary persistence of fetal hemoglobin, hemoglobin with high P2 window, hemoglobin with high P3 window etc, Among the cases with abnormal hemoglobin disorders, 744 (53.9%), 545 (39.5%) and, 91 (6.6%) cases were found to have the heterozygous, homozygous and, double heterozygous state. Of the 188 ante-natal cases screened, 31.4% of cases had abnormal hemoglobin variants with sickle cell disorders being the most prevalent one.

Conclusion:

Along with the high occurrence of sickle cell disorders in the study area, some other rare hemoglobin disorders are also prevalent which calls for a large community-based cohort study.

Clinical variability and molecular characterization of Hbs/Gγ (Aγδβ)0-thal and Hbs/HPFH in Indian sickle cell disease patients: AIIMS experience

INTRODUCTION

In sickle cell disease (SCD) patients, among the predictors of survival, HbF levels play a significant role in lowering the morbidity and mortality. Coinheritance of δβ thalassemia and hereditary persistence of fetal hemoglobin (HPFH) may contribute to variable HbF levels in SCD patients, thus influencing their clinicopathological profile. Such cases are sparsely documented in the literature and thus, we screened the presence of δβ thalassemia and HPFH in 126 cases of SCD with high HbF.

MATERIAL AND METHODS

A total 126 SCD individuals with raised HbF levels were the study subject. Capillary zone electrophoresis (CZE) was done for the quantitative assessment of hemoglobin variants. HbSC, HbSD, HbAS and HbSE cases were excluded. Asian Indian Gγ(Aγδβ)0-thal, δβ0-thal (Sicilian, 13.4 kb), (Chinese, 100 kb), HPFH-1 (Black, 106 kb), HPFH-2 (Ghanaian, 105 kb), HPFH-3 (Indian, 48.5 kb) were done by GAP-PCR.

RESULTS

Out of 126, 78 cases (62%) were homozygous for SCD. The remaining 48 cases suspected to be heterozygous were furthered screened and 6/48 cases (12.5%) were found to be compound heterozygous. Out of these 6 cases,4(66.66%) had HbS/ δβ- Gγ(Aγδβ)0 and 2(33%) had HbS/HPFH compound heterozygous condition. None of the patients had δβ0-thal (Sicilian, 13.4 kb), (Chinese, 100 kb), HPFH-1 (Black, 106 kb), HPFH-2 (Ghanaian, 105 kb).

CONCLUSION

This study highlights the importance of understanding the complex patho-physiology of compound heterozygous cases of HbS/HPFH and HbS/δβ thalassemia, as these infrequent conditions lead to change in phenotype and clinical severity of the disease. Insight into more such cases will open the window to better analyze the disease pathogenesis in these rare compound heterozygous conditions, as this will be beneficial to formulate proper management protocol in these patients.

Effect of Assorted Globin Haplotypes and α-Thalassemia on the Clinical Heterogeneity of Hb S-β-Thalassemia

Hemoglobinopathies and thalassemias are the most commonly encountered monogenic disorders of blood in humans, posing a major genetic and public health problem round the globe. Hb S (HBB: c.20A>T)-β-thalassemia (β-thal) is a compound aberrant heterozygosity with inconsistent phenotypic expression, which are poorly described and clinically mapped. Comprehensive genetic characterization of such a population is highly warranted for complete understanding of the clinical heterogeneity, disease prognosis and therapeutic management. In this study, Hb S-β-thal (n = 60) patients, strictly defined by varying degrees of clinical presentations, were selected to evaluate their genotype-phenotype agreement. Furthermore, β-globin (n = 120) and α-globin gene clusters (n = 60) were genetically characterized and statistically correlated with clinical terminologies to explain the clinical heterogeneity. Our results revealed the association of the Arab-Indian haplotypes with nine different frameworks of β-thal together with the modulating role of α-thalassemia (α-thal). The study subjects, including carriers of β-thal haplotype III [- - - - - - -] (8.0%), presented with varying severe patterns of clinical symptoms such as painful crisis, multiple infections and splenomegaly, as an outcome of significantly less Hb F and higher Hb S levels (p < 0.5). The study findings indicated that together with α-thal, β-thal haplotypes and Hb F levels, may possibly provide a close justification to support the clinical heterogeneity in the study population.

The clinical severity of hemoglobin S/Black (A γδβ)0 -thalassemia

Hemoglobin S/Black (^A γδβ)⁰ -thalassemia is a rare sickle cell disease (SCD) variant. On the basis of limited descriptions in the literature, the disease is reported as a mild microcytic anemia with an uncomplicated course. We report the clinical and laboratory data of nine patients whose diagnoses were confirmed by DNA-based techniques. Despite having mild anemia and high fetal hemoglobin level postinfancy, these patients developed many of the classic complications of SCD, including vaso-occlusive crisis, acute chest syndrome, avascular necrosis, and cholelithiasis. On the basis of these findings, we recommend that patients with this rare disorder receive specialized hematology care according to SCD guidelines.

Clinical events in a large prospective cohort of children with sickle cell disease in Nagpur, India: evidence against a milder clinical phenotype in India

BACKGROUND

The clinical phenotype of sickle cell disease (SCD) has been reported to be milder in India than in the United States. The objective of this large single-center study was to examine the rate of complications to define the phenotype of SCD in India.

METHODS

The rate of complications per 100 person-years in 833 pediatric SCD patients for 1954 person-years in Nagpur, India including those diagnosed on newborn screen (NBS) and those presenting later in childhood (non-NBS) was compared to those reported in the cooperative study of sickle cell disease (CSSCD). Event rates were also compared between patients belonging to scheduled castes (SCs), scheduled tribes (STs), and other backward classes (OBC).

RESULTS

Comparison of CSSCD versus Nagpur NBS versus Nagpur non-NBS for rates of pain (32.4 vs. 85.2 vs. 62.4), severe anemia (7.1 vs. 27 vs. 6.6), stroke (0.7 vs. 0.8 vs. 1.4), splenic sequestration (3.4 vs. 6.7 vs. 1.6), acute chest syndrome (24.5 vs. 23.6 vs. 1.0), and meningitis (0.8 vs. 0 vs. 0.1) revealed more frequent complications in Nagpur compared to CSSCD. Comparison of ST, SC, and OBC for rates of pain (84.6 vs. 71.9 vs. 63.5), acute chest syndrome (3.6 vs. 2.8 vs. 2.2), severe anemia (5.4 vs. 9.5 vs. 11.4), stroke (1.2 vs. 0.4 vs. 0.3), splenic sequestration (0.6 vs. 2.4 vs. 1.9), and meningitis (0.8 vs. 0 vs. 0.1) revealed significantly more frequent complications among ST.

CONCLUSIONS

SCD-related complications are more frequent in Indian children than that observed in CSSCD. Further study is indicated to define SCD phenotype in India.