The co-inheritance of alpha-thalassemia and sickle cell anemia is associated with better hematological indices and lower consultations rate in Cameroonian patients and could improve their survival

PLoS One. 2014 Jun 30;9(6):e100516. doi: 10.1371/journal.pone.0100516. eCollection 2014.


Background: Co-inheritance of α-thalassemia was reported to be associated with a delayed age of disease onset among Cameroonian Sickle Cell Anemia (SCA) patients. The present study aimed to explore the correlation between α-thalassemia, hematological indices, and clinical events in these patients.

Methods and findings: We studied 161 Cameroonian SCA patients and 103 controls (59.1% HbAA) with median ages of 17.5 and 23 years. RFLP-PCR was used to confirm SCA genotype and to describe haplotypes in the HBB-like genes cluster. Multiplex Gap-PCR was performed to investigate the 3.7 kb α-globin gene deletions. SNaPshot PCR, capillary electrophoresis and cycle sequencing were used for the genotyping of 10 SNPs in BCL11A, HMIP1/2, OR51B5/6 and HBG loci, known to influence HbF levels. Generalised linear regression models adjusted for age, sex and SNPs genotypes was used to investigate effects of α-thalassemia on clinical and hematological indices. The median rate of vaso-occlusive painful crisis and hospitalisations was two and one per year, respectively. Stroke was reported in eight cases (7.4%). Benin haplotype was the most prevalent (66.3%; n = 208 chromosomes). Among patients, 37.3% (n = 60) had at least one 3.7 kb deletion, compared to 10.9% (n = 6) among HbAA controls (p<0.001). Among patients, the median RBC count increased with the number of 3.7 kb deletions [2.6, 3.0 and 3.4 million/dl, with no, one and two deletions (p = 0.01)]. The median MCV decreased with the number of 3.7 kb deletion [86, 80, and 68fl, with no, one and two deletions (p<0.0001)], as well as median WBC counts [13.2, 10.5 and 9.8×109/L (p<0.0001. The co-inheritance of α-thalassemia was associated with lower consultations rate (p = 0.038).

Conclusion: The co-inheritance of α-thalassemia and SCA is associated with improved hematological indices, and lower consultations rate in this group of patients. This could possibly improve their survival and explain the higher proportion of α-thalassemia among patients than controls.

MeSH terms

  • Adolescent
  • Adult
  • Age Factors
  • Anemia, Sickle Cell / blood
  • Anemia, Sickle Cell / complications
  • Anemia, Sickle Cell / genetics*
  • Anemia, Sickle Cell / mortality
  • Blood Cell Count
  • Cameroon
  • Female
  • Gene Deletion
  • Haplotypes
  • Hemoglobin A / genetics*
  • Hemoglobin, Sickle / genetics*
  • Humans
  • Inheritance Patterns
  • Male
  • Multigene Family
  • Polymorphism, Single Nucleotide
  • Referral and Consultation / statistics & numerical data
  • Survival Analysis
  • alpha-Globins / genetics*
  • alpha-Thalassemia / blood
  • alpha-Thalassemia / complications
  • alpha-Thalassemia / genetics*
  • alpha-Thalassemia / mortality
  • beta-Globins / genetics


  • Hemoglobin, Sickle
  • alpha-Globins
  • beta-Globins
  • hemoglobin AA
  • Hemoglobin A

Grants and funding

The molecular experiments of the study were funded by the National Health Laboratory Services, South Africa; the University Research Committee and Carnegie Research Development Grant, University of Cape Town, South Africa. The students' bursaries were provided by the National Research Foundation-DAAD scholarship, South Africa, and the Third World Academy of Sciences. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.