E-Book

E-Book 3rd Congress

  • Sickle Cell Anemia in Khorasan-Razavi : Co-Inheritance of αThalassemia, Clinical & Hematological Characterizations
  • Tayebeh Hamzehloei,1,* Hamed Miri,2 zahra Malekdadi,3
    1. Mashhad university of medical science, medical genetic department, Mashhad-Iran
    2. Mashhad university of medical science, medical genetic department, Mashhad-Iran
    3. Mashhad university of medical science, medical genetic department, Mashhad-Iran


  • Introduction: Although sickle cell anaemia (SCA) is genetically characterised by a single point mutation, patients can manifest varying degrees of clinical severity due to various genetic modulators that affect the phenotype of this disease. The co-inheritance of alpha-thalassemia (α-thalassemia) has been associated with a milder phenotype in SCA patients, but could also result in the increase of vaso-occlusive (VOC) pain episodes. The present study explored the correlation between α-thalassemia, haematological indices, and clinical events in SCA patients.
  • Methods: For this cross-sectional study, a full blood count and clinical phenotype profile was collected for 262 anemic individuals. Restriction fragment length polymorphism - polymerase chain reaction (RFLP-PCR) was performed for the molecular diagnosis of SCA. Multiplex Gap-PCR was performed to investigate the 3.7kb and 4.2kb α-thalassemia gene deletions.
  • Results: There were 178 SCA patients (HbSS), 32 carriers (HbAS) and 52 unaffected individuals (HbAA), with median ages of 18, 23 and 26 years, respectively. Among patients, 57% (101) had less than three vaso-occlusive pain crises (VOCs) per year. The median haemoglobin (HbA) level was 7.8g/dl for patients, 12.7g/dl for carriers and 13g/dl for unaffected individuals. Up to 37.1% (66) of SCA patients (HbSS) co-inherited α-globin gene deletions, compared to the 20% (10) prevalence of these gene deletions in the unaffected (HbAA) and carrier (HbAS) cohorts. Among patients, the genotype distribution was 30.3% (54) αα/α-3.7 (one 3.7kb αglobin gene deletion), 6.8% (12) α-3.7/α-3.7 (two 3.7kb α-globin gene deletions), and none had the 4.2kb deletion. Among patients, the median red blood cell count (RBC) increased with the number of 3.7kb deletions [2.6, 3.0 and 3.4 million cells/dl, with no, one and two deletions, respectively (p=0.01)]. The median mean corpuscular volume (MCV) [86, 80 and 68fL, with no, one and two deletions, respectively (p <0.0001) and the median white blood cell count (WBC) [13.2, 10.5 and 9.8 X 109/L with no, one and two deletions, respectively (p<0.0001) and the median white blood cell count (WBC) [13.2, 10.5 and 9.8 X 109/L with no, one and two deletions, respectively (p<0.0001) decreased with an increase in the number of 3.7kb deletions. An analysis of the effect of the co-inheritance of α-thalassemia and SCA on the haematological parameters revealed a significantly lower lymphocyte and monocyte count, which is known to be associated with a better clinical phenotype. In addition, the co-inheritance of α-thalassemia was significantly associated with a delayed age of disease onset among Khorasan Razavi SCA patients. Furthermore, after performing linear logistic regression analysis, the co-inheritance of α-thalassemia was associated with a lower consultation rate (p=0.038).
  • Conclusion: The co-inheritance of α-thalassemia with SCA was associated with an improved haematological profile, with an increase in the number of α-globin gene deletions. The possible positive effect of the co-inheritance of α-thalassemia on SCA patients’ survival could explain the high proportion of α-thalassemia among SCA patients when compared to the unaffected controls. These results have implications for disease management in Khorasan Razavi in terms of genetic counselling and the detection of SCA.
  • Keywords: MUTATION, SICKLE CELL, THALASSEMIA