Abstract
INTRODUCTION: Hb E-beta thalssemia has variable clinical phenotype, varying from NTDT to severe transfusion dependent thalassemia. Factors influencing the severity include HbF level, type of beta mutation, co-inheritance of alpha mutation (including triplication and quadruplication), and various polymorphisms. We evaluate the possible correlation between HbE levels and clinical severity in patients in Hb E-beta thalassemia.
AIMS AND OBJECTIVES: To study the phenotypic heterogeneity of Hb E-beta thalassemia patients with respect to Hb E levels.
MATERIALS AND METHODS: Patients >18years were enrolled and evaluated for clinical phenotype as per Mahidol score (age of onset, age of first transfusion, requirement for transfusion, spleen size, growth retardation and steady-state hemoglobin), and classified into mild, moderate and severe. Further biochemical data was evaluated including serum ferritin. The clinical phenotype severity was correlated with HbE and HbF levels. Patients on disease modifying drugs (eg hydroxyurea) were excluded.
RESULTS: A total of 120 patients of Hb E-beta thalassemia were enrolled with M:E = 1.1:1. 65.8% patients were 18-30 years age range, while 5.8% were above 50years of age. As per Mohidol score, 39.2% (47) patients were mild, 45.8% (55) were moderate and 15% (18) were severe phenotype. Observations amongst patients of different clinical severity are as shown in Table 1.
| Character | Mild | Moderate | Severe | Range | P value |
|---|---|---|---|---|---|
| Number | 47 | 55 | 18 | ||
| Baseline Hb (g/dl) | 7.9+-0.9 | 6.4+-1.1 | 6.2+-0.7 | 3.8-10.3 | 0.000 |
| Age at presentation (years) | 18.3+-8.76 | 13.1+-8.0 | 3.16+-2.08 | 1-44 | 0.000 |
| Age at 1st transfusion (years) | 22.1+-11.4 | 15.1+-8.76 | 3.9+-1.9 | 1-60 | 0.000 |
| Freq of transfusion (annual) | 2.5+-4.5 | 12.2+-7.6 | 19.3+-11.4 | 0-48 | 0.000 |
| Spleen size (cms) | 5.6+-2.4 | 7.8+-2.9 | 10.4+-3.4 | 0-15 | 0.000 |
| Serum ferritin (ng/ml) | 792.5+-534.6 | 1206.5+-523.9 | 1570.5+-581.2 | 64.2-2924.2 | 0.000 |
| Character | Mild | Moderate | Severe | Range | P value |
|---|---|---|---|---|---|
| Number | 47 | 55 | 18 | ||
| Baseline Hb (g/dl) | 7.9+-0.9 | 6.4+-1.1 | 6.2+-0.7 | 3.8-10.3 | 0.000 |
| Age at presentation (years) | 18.3+-8.76 | 13.1+-8.0 | 3.16+-2.08 | 1-44 | 0.000 |
| Age at 1st transfusion (years) | 22.1+-11.4 | 15.1+-8.76 | 3.9+-1.9 | 1-60 | 0.000 |
| Freq of transfusion (annual) | 2.5+-4.5 | 12.2+-7.6 | 19.3+-11.4 | 0-48 | 0.000 |
| Spleen size (cms) | 5.6+-2.4 | 7.8+-2.9 | 10.4+-3.4 | 0-15 | 0.000 |
| Serum ferritin (ng/ml) | 792.5+-534.6 | 1206.5+-523.9 | 1570.5+-581.2 | 64.2-2924.2 | 0.000 |
Hb E levels of the patients ranged from 28% to 83.5%, and HbF levels ranged from 3.1% to 49.4%. On statistical analysis, difference in HbE levels was significant between severe vs mild and intermediate groups (p=0.0005 and 0.012 respectively), but not amongst mild vs intermediate groups (p=0.21). Also, difference in HbF levels was significant between mild vs moderate and severe groups (p=0.007 and 0.004 respectively), but not between moderate vs severe groups (p=0.26). Regression analysis showed HbF and HbE to be independent parameters of severity and both have negative correlation with disease severity.
CONCLUSION: HbE is an independent parameter of severity and correlated negatively with disease severity in HbE-beta thalassemia.
No relevant conflicts of interest to declare.
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