NSFUSION 

ON SCIENTI 

BLOOD TS 

OGY AND 87 

STS SOCIET 

African Journal of Laboratory Haematology 

and Transfusion Science Volume 1, Issue 2&3: page 158–172 2022. ARTICLE ID: 2022–AJLHTS–0016 

www.hbtssn.org/ajlhts ISSN (Print):2814–0591; (Online): 2814–0605 

N 

KEMATOLO 

DIAGNOSIS 

, Hin 

GEOIN 30 

OSIS & SERVI 

09 

SERVICE 

ORIGINAL ARTICLE 

Association of BCL11A and HBS1L–MYB Polymorphisms in Sickle Cell Anaemia Subjects of Different Age Groups in Nigeria Zakariyahu T. O‘ and Ajayi, O.12. 

‘Haematology and Blood Transfusion Service Department, LAUTECH Teaching Hospital, Ogbomoso. 

Abstract Background Haematological features and clinical severity of Sickle Cell Anaemia (SCA) are influenced by age, gender, genetic and community factors. BCL11A is cytogenetically located on short arm of chromosome 2 at position 16.1 while it is located at base pair 60,451,167 to 60,553,498 on chromosome 2 at the molecular level. Polymorphisms in the HBS1L MYB Intergenic region were associated with F–cell levels and accounted for 19.4% of the F–cell variance in normal Europeans. 

Department of Physiology, University of Benin. Benin City 

Objective This study highlights possible effects of age in Haemoglobin F Induction through possible association of BCL11A and HBS1L–MYB genes polymorphism in SCA Subjects population in Oshogbo metropolis. 

Correspondence Author: Zakariyahu T. O, Haematology And Blood Transfusion Service department, LAUTECH Teaching Hospital, PMB 4007, Ogbomoso. Email address: tawaasande2020@gmai l.com 

Materials and Methods 

Thirty–Six SCA subjects were recruited with ages ranging between 1 and 40years divided into five groups of eight subjects each except age ranges 21 to 25 and 25 to 40 years which were six subjects each, while ten haemoglobin A subjects served as control for all age ranges. Red Cell indices and gene analysis such as HCT, RBC Count, Haemoglobin concentration, Hb F level, BCL11A and HBS1L–MYB genes were studied using standard methods. 

Received: May 01, 2022, Accepted: August 29, 2022 Published: September 30, 2022 

Results Results shows no statistically significant difference in fetal haemoglobin between control and subjects (P>0.05). There was a statistical decrease in haemoglobin level in the test subjects compared to controls. Also, the HBS1L–MYB protein expression was not significantly different in Haemoglobin A subjects and the SCA 

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subjects, but there was a statistically significant decrease in BCL11A gene expression in SCA Subjects compared to Haemoglobin A Subjects (P<0.05). A statistically significant decrease in BCL11A gene expression was obtained in ages 16 to 20 and 21 to 40years age groups (p<0.05). There was a positive correlation between Fetal Haemoglobin and haematocrit and haemoglobin levels (r=0.04341, p=0.2227); (r=0.01705, p=0.4479), respectively. The correlation between Fetal haemoglobin and BCL11A and HBS1L–MYB showed statistically significant negative correlations (r= –0.1220, p=0.0368), r= –0.1260, p=0.0336 respectively). 

Conclusion Conclusively, BCL11A and HBS1L–MYB genes promote induction of fetal haemoglobin in SCA subjects compared with controls recruited for this study. 

Keywords: BCL11A, HBS1L–MYB, Sickle Cell Anaemia, Age, Osogbo Metropolis. 

Introduction Sickle Cell Disease (SCD) is a structural haemoglobinopathy associated with hereditary haemolytic anaemia with its clinical phenotype resulting from several genotypes (1,2). It is the first molecular disease described associated with a mutated protein (3), resulting from inheritance of two abnormal allelomorphic genes that control the formation of beta globin chain. This results in the production of abnormal less soluble haemoglobin S (Hb S), which tends to polymerize and deform red blood cells into the characteristic sickle shape (4). 

A strong correlation has been established between the clinical severity and the level of fetal haemoglobin (HbF) in SCD (5). The expression of HBG1(142200) and HBG2 (14250) genes, critical for the synthesis of Hbf, is dramatically reduced shortly before birth and remains as such after birth (6). Rarely, the level of Hbf may remain significantly elevated a condition known as Hereditary Persistence of 

Fetal Haemoglobin (HPFH) (7). Inhibition of sickling by high levels of Hbf has been documented. This is as a result of ability of Hbf to decrease the polymerization of deoxygenated Hb S (8). Interestingly, HPFH shows to be beneficial in SCD (7). Up to three quantitative traits loci has been associated with HPFH. These are – the combined Xmnl–158 and ORS1B516 locus on chromosome 11p15.4 (9), the HBS1l–MYB intergenic polymorphism (HMIP) locus on chromosome 6q23.3 (10) and the BCL11A locus on chromosome 2q16.1 (11). 

The fetal to adult haemoglobin switch and silencing of fetal haemoglobin have been an area of long–standing interest given the fact that clinical induction of Hb F production holds tremendous promise in ameliorating the clinical symptoms of SCA and beta thalassemia as stated in previous reports (12,13,14). Successful induction of Hb F depends on the physiological condition of SCA individual. This study is therefore designed to determine the possible effects of age on Hb F induction through 

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association of BCL11A and HBS1L–MYB genes polymorphisms in SCA Subjects population in Osogbo metropolis. 

Materials and Methods 

Study design: This hospital based, cross sectional descriptive study was carried out in Osogbo, the capital of Osun State in the South western part of Nigeria. 

Subjects: A total of Thirty–six (36) steady–state SCD patients attending Haematology and Paediatrics clinics who met the inclusion criteria were recruited for the study. Additionally, 10 Hb AA individuals were also recruited to serve as controls. 

Ethical Consideration: Ethical approval was obtained from the Ethical Committee of LAUTECH Teaching Hospital, Osogbo. Written informed consent/assent was also obtained as appropriate from individuals prior to their enrolment into the study. Confidentiality was assured for every subject and their results. 

Conduct of the study: These participants were categorised, using Stratified Random Sampling with age as the characteristic of interest as follows: 1-5yrs, 6-10yrs, 11-15yrs, 16-20yrs and 21-40yrs, eight samples per age group of test categories one to three, six samples each were used for categories four and five while two samples per category for control were studied. 

Inclusion criteria: 

160 

Sickle cell disease subjects with Haemoglobin genotype SS as well as Hb AA controls. 

Consenting participants must be greater than 18 yrs. 

Assenting participants must be greater than 6yrs and less than 18 years of age 

Minor for which parent’s consent has been sought 

Exclusion criteria: 

Patient that had been transfused with blood or hospitalized in the past 6 weeks prior to the time of sample collection. Patient currently treated with hydroxyurea. 

Sample Collection 

Three millilitres of venous blood was collected from each subject through aseptic venepuncture and dispensed as follows. Two millilitres was dispensed into an EDTA bottle while the remaining 1mL was dispensed into the DNA/RNA Shield Fluid bottle without mixing. 

Haematological Parameters 

Complete Blood Count: The hemogram of all samples were determined by automation method using Sysmex KN21X 3- parts differential Auto Haematology Analyzer through the Coulter Principle of Electrical Impedance while estimation of Hb F was carried out using the Modified Betke’s Method (15) based on the principle of alkaline denaturation test. 

Polymerase Chain Reaction- Restriction Fragment Length Polymorphism (PCR RFLP) method for BCL11A and HBS1L–MYB gene analysis 

DNA was extracted from blood using SDS–proteinase K as described by Francesco et. al., (12) with the kit Zymo–Spin Technology using Quick–DNA Miniprep Plus kit (Catalog Nos D4068 and D4069) while the DNA yield was done spectrophotometrically. 

Tm 

Polymerase Chain Reaction (PCR) and Restricted Fragment Length Polymorphism were carried out according to Gaurab (17). 

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differences. P value less than 0.05 was taken to be statistically significant. 

Data Analysis Data were collated using Microsoft Word and Excel package, while statistical analysis was carried out using GraphPad Prism 8.0. Results were presented in tables and figures – bar charts and correlation graphs. Student‘s t–test and ANOVA were used to compare group 

RESULTS Results are presented in tables and figures as shown below: 

LIL 

Table 1: Distribution of Age Groups of Sickle Cell Anaemia Subjects Recruited for the Research 

Age Range (Years) Frequency Percentage (%) Mean + SE (12.39+1.31) 

1–5 

6 – 10 

11 – 15 

12.61 

16–20 

21 – 40 

Total 

Table 2: Distribution of Age Groups of Haemoglobin A Controls Recruited for the Research 

Age Range (Years) 

Frequency 

Percentage (%) 

Mean + SE (15.13.41) 

1–5 

6 – 10 

11 – 15 

15.1 

16–20 

21 – 40 

Total 

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Fetal Haemoglobin (%) 

Figure 1: The percentage fetal haemoglobin in Haemoglobin A Subject (Control) and Sickle Cell Anaemia Subjects (test group). The result shows no statistically significant difference in fetal haemoglobin between control and test subjects (p>0.05). 

Control 

Test 

** 

HGB (g/dL) 

Figure 2: The haemoglobin concentration in haemoglobin A Subject (Control) and Sickle Cell Anaemia Subjects (test group). 

A statistically significant decrease haemoglobin concentration in the test subjects was obtained when compared with control (p<0.05). 

Test 

Control 

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HSB1L–MYB (KB) 

BCL11A (KB) 

25000 

20000 

15000 

10000 

5000 

0 

50000 

40000 

30000 

20000 

10000 

0 

Zakariyahu & Ajayi / BCL11A and HBS1L–MYB Polymorphisms in SCA 

Control 

T 

Afr J Lab Haem Trans Sci 2022, 1(2): 158 – 172 

Control 

Test 

*** 

Test 

Figure 3: The HBS1L MYB gene expression in haemoglobin A Subject (Control) and Sickle Cell Anaemia Subjects (test group). 

The HSB1L–MYB gene expression is higher in Haemoglobin A subjects compared with Sickle Cell Anaemia Subjects, though the difference is not significant (p>0.05) 

Figure 4: The BCL11A gene expression in haemoglobin A Subject (Control) and Sickle Cell Anaemia Subjects (test group). 

There was a statistically significant decrease in BCL11A gene expression in Sickle Cell Anaemia subjects compared with Hamoglobin A subjects (p<0.05). 

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Fetal Heamoglobin (mm Hg) 

Test 

Control 

1–5yrs 

6–10yrs 

16–20yrs 

21–40yrs 

11–15yrs Age groups 

Figure 5: The fetal haemoglobin level among different age groups of test and control subjects. The result shows no significant difference in fetal haemoglobin concentration among different age groups (1 –5, 6 to 10, 11 to 15, 16 to 20, 21 to 40) compared to control (p>0.05). 

70000 

60000 

50000 

540000 

Test 

BCL11A Gene 

230000 

Control 

20000 

10000 

1–5yrs 

6–10yrs 

16–20yrs 

21–40yrs 

11–15yrs Age Groups 

Figure 6: The BCL11A gene expression among different age groups of tests and control subjects. The result shows a statistically significant decrease in BCL11A gene expression in 16 to 20 and 21 to 40 age groups but, no statistically significant difference in 1 to 5, 6 to 10 and 11 to 15 age groups compared to control (p<0.05). 

ce 

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30000 

25000 

a 20000 

HBSIL–MYB Gene 

15000 

Test 

Control 

10000 

5000 – 

0 

1–5yrs 

6–10yrs 

16–20yrs 

21–40yrs 

11–15yrs Age Groups 

Figure 7: The HBS1L–MYB gene expression among different age groups of test and control subjects. Result show no significant difference in HBS1L–MYB gene expression among different age groups of SCA subjects compared to control subjects (p>0.05). 

150 

r=0.04341 p=0.2227 

Fetal Haemoglobin (%) 

0 

10 

30 

40 

20 HCT (%) 

Figure 8: The correlation between fetal haemoglobin and haematocrit value. The result shows a positive correlation between fetal haemoglobin and haematocrit but was not statistically significant (r=0.4341, p=0.2227). 

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Fetal Haemoglobin (%) 

166 

150 

Fetal Haemoglobin (%) 

100 

50 

150 

0 

HGB (g/dl) 

Figure 9: The correlation between fetal haemoglobin and haemoglobin concentration. Fetal haemoglobin and Haemoglobin concentration results show a positive correlation but was not statistically significant (r=0.01705, p=0.4479). 

100 

50 

r=0.01705 p=0.4479 

0 

5 

10000 

10 

r=0.1260 p=0.0336* 

15 

20000 30000 40000 

HSB1L–MYB (KB) 

Figure 10: The correlation between fetal haemoglobin and HSB1L–MYB gene expression Result shows a statistically significant negative correlation between HSB1L–MYB and Fetal haemoglobin. 

gene expression 

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r=0.1220 p=0.0368* 

Fetal Haemoglobin (%) 

0 

40000 

50000 

10000 20000 30000 

BCL11A (KB) 

Figure 11: The correlation between fetal haemoglobin and BCL11A gene expression. A statistically significant negative correlation was obtained between fetal haemoglobin and BCL11A gene expression (r= –0.1220, p=0.0368). 

50000 

40000 

r=0.07899 p=0.0968 

30000 

BCL11A (KB) 

20000 

10000 

5 

10 HGB (g/dL) 

Figure 12: The correlation between BCL11A gene and haemoglobin concentration The result shows a negative correlation between BCL11A gene expression and haemoglobin concentration but was not statistically significant (r= –0.07899, p=0.0968). 

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40000 

r=0.01356 p=0.4988 

30000 

HSB1L–MYB (KB) 

E 20000 

10000 

0+ 

1 5 

10 

15 

HGB (g/dl) 

Figure 13: The correlation between HSB1L–MYB gene expression and haemoglobin concentration. Result shows a negative correlation between HSB1L–MYB gene expression and haemoglobin concentration but was not statistically significant (r= –0.01356, p= 0.4988). 

DISCUSSION Haematological features and clinical severity of SCD are influenced by age, gender, genetic, and environmental factors. The presence of a– thalassaemia, variation in Hb F level, and the specific haplotype background that is linked to the B globin gene play an important role in the severity of disease (18). This study highlights possible effects of age on Hb F induction through possible association of BCL11A and HBS1L–MYB genes polymorphism in SCA subject population in Osogbo metropolis. 

In this study, results show no statistically significant difference in fetal haemoglobin between control and test subjects (p>0.05). This outcome is at variance with a similar study conducted by Uko et al., (19) who reported a higher mean Hb F value in Hb SS subjects (3.05+1.61%) compared to Hb AA controls (0.20+0.25). In another study conducted by 

Adekile et al., (20), they showed that complications rarely occurred before 5 years of age when the haemoglobin F level was approximately 30%, but with increasing age and decline in haemoglobin F level, clinical complications begin to occur. Hb F may therefore have a beneficial effect on the prognosis of sickle cell disease and use of therapeutic approaches involving combination of Hb F–inducing agents in the management of patients with SCD (21). 

The HSB1L–MYB gene expression was relatively stable in Haemoglobin A and sickle cell subjects (p>0.05). This outcome is contrary to the report of Farrell et al., (22) who stated that HBS1L–MYB intergenic polymorphism is associated with Hb F among sickle cell anaemia patients of African descent, although much less significantly compared with Europeans or Chinese because of their much lower minor 

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allele frequencies. It could be that there are other HMIP variants associated with Hb F level among people of African descent that are not tracked well by SNP rs9399137 (23). In another study, only HBS1L expression was correlated with elevated Hb F levels (24). However, higher level of HSB1L–MYB gene in haemoglobin A subjects when compared with control could be as a result of other genetic makeup and environmental factor. The relatively stable HBF in the controls and subjects in this study apparently has a direct link to the unchanged expression of the gene among the groups 

studied. 

The BCL11A rs1427407 variant is commonly found in SCD patients (25). This study revealed a statistically significant decrease in BCL11A gene expression in sickle cell anaemia subjects compared to hamoglobin A subjects (p<0.05). The outcome in this study is contrary to Hassan et al., (26) who reported that SCD patients had plasma BCL11A levels that were significantly higher than the control subjects (P<0.05). 

Furthermore, the SCD patients had a higher frequency of the GG and GT 

genotypes at BCL11A rs1427407. Moreover, the BCL11A rs1427407 GG variant increased the risk of developing SCD. Some studies have also indicated that BCL11A can be used to predict overall and disease–free survivals (27, 28). The down regulation of this gene as seen in this study could be associated with the stable states of the subjects studied. Lower expression of BCL11A has been associated with a better efficiency in the switch of embryonic haemoglobin to fetal haemoglobin (11). Also, Funnell et al., (29) stated that the increase in the expression of the BCL11A gene will lead to lower levels of Hb F. The BCL11A genotype most associated with Hb F expression correlates with reduced BCL11A expression since it acts as a repressor and acts directly on 

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the HBB cluster, participating in Hb switching at different development stages (30). This study has demonstrated a direct agreement with these observations. 

Furthermore, this study demonstrated a significant negative correlation between Hb F and BCL11A gene expression (r=0.1220) expression as well as that of HSB1L–MYB (r=0.1260). 

In a similar study conducted by Thein et al., (10) only HBS1L expression was correlated with elevated Hb F levels. Nevertheless, the expression profile of MYB and HBS1L in adults with non–gene deletion HPFH was downregulated. Overexpression of MYB in K562 cells inhibited HBG expression (27). Low levels of MYB were associated with reduced cell expansion and accelerated erythroid differentiation, suggesting that variation in the intrinsic levels of MYB might affect Hb F by its effect on the cell cycle. Overexpression of microRNA–15a and -16-1 down–regulated MYB in CD34* erythroid progenitors and increased Hb F (24). There were limited studies on Association of BCL11A and HBS1L–MYB Polymorphism in Sickle Cell Anaemia Subjects with different age groups as the characteristic of interest hence, limited previous studies were available to support results with age ranges. 

The BCL11A rs1427407 variant is commonly found in SCD patients (25). The BCL11A gene was first detected in B–cell chronic lymphocytic leukemia and is a proto oncogene for malignant hematological diseases (32). In a study conducted by Hassan et al., (26), SCD patients had plasma BCL11A levels that were significantly higher than the control subjects (100.13 μg/L versus 70.88 μg/L, P<0.05). This study showed a statistically significant decrease in BCL11A gene expression in 16 to 20 and 21 to 25 age groups but, no statistically significant difference in other age 

groups. 

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al., (35), BCL11A correlates most strongly with Hb F expression from the action of SNPs located within a region of about 14 kb in intron 2 of the gene. The BCL11A genotype most associated with Hb F expression correlates with reduced BCL11A expression since it acts as a repressor and acts directly on the HBB cluster, participating in Hb switching at different developmental stages (30). 

The sequences of HBS1L and MYB and other genes are uninformative regarding Hb F regulation (36). This study shows a negative correlation between HSB1L–MYB gene expression and haemoglobin concentration but was not statistically significant (r= –0.01356, p=0.4988). Results show no statistically significant difference in HBS1L–MYB gene expression in the different age groups (1 to 5, 6 to 10, 11 to 15, 16 to 20, 21 to 25) compared to control (p>0.05). 

Fetal hemoglobin (Hb F) is the major genetic modulator of the haematologic and clinical features in health and disease state. HbF is the predominant hemoglobin from early gestation until 1 to 2 months post–natal when adult Hb A predominates (6). In this study, there was a positive correlation between fetal haemoglobin and haematocrit value (r=0.04341, p=0.2227) and also between fetal haemoglobin and haemoglobin concentration ((r=0.01705, p=0.4479). The positive correlation between Hb F and haemoglobin, and Hb F and haematocrit percentage could be as a result of erythroid precursors of normal adults expressing haemoglobin concentration at a level. According to Stamatoyannopoulos (13), a stochastic model posits that the increase in HbF is as a result of recruitment of erythroid progenitor cells that prematurely undergo terminal differentiation and are committed to producing y–globin and the fetal haemoglobin level among different age groups of test and control subjects. 

This study equally showed no statistically significant difference in fetal haemoglobin concentration in different age groups (1 to 5, 6 to 10, 11to 15, 16 to 20, 21 to 40) compared to controls (p> 0.05 respectively). This is at variance with Olaniyi et al., (33) which posited that there was a statistically significant difference in the mean level of Hb Fin (5.16+/– 4.04) patients compare to control (1.04+/–0.44). In another study, Tshilolo et al. (34) submitted that Congolese SCA patients displayed low level Hb F and F–cells that contribute to the severity of SCA. It could be that there are other HMIP variants associated with Hb F level among people of African descent that are not tracked well by SNP rs9399137 (23). 

This study shows a negative correlation between BCL11A gene expression and haemoglobin concentration but was not statistically significant (r= –0.07899, p=0.0968). In a similar study conducted by Sedgewick et. 

Conclusion Expression of BCL11A and HBSIL–MYB genes have established roles in regulation of Haemoglobin F among SCA and control subjects in Osogbo, Southwest Nigeria. As age advances, the BCL11A expression reduces from age 16 upward. The HBS1L–MYB gene remain with attendant influence on Hb F to the age of 40 in the studied population. Knocking down of BCL11A protein synthesis poses a promising role in induction of fetal haemoglobin and reduces sickle haemoglobin production with pancellular distribution of fetal haemoglobin, which in SCD is sufficient to mitigate hemolysis and significantly reduce vaso–occlusive crisis. 

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16. 16. 
17. 17. 
18. 18. 
19. 19. 

Reference 

9. 9. 1. Steinberg, M.H. (2008). Sickle 

Cell Anaemia, the First Molecular Disease, Overview of Molecular Etiology, Pathophysiology, and Therapeutic Approaches. Science World Journal, 8, 1295–1324. Chakravorty, S. & Williams, T.N. (2015). Sickle cell disease: 10. A neglected chronic disease of increasing global health importance. Archives of Disease in Childhood, 100(1), 48–53. Pauling, L., Itano, H.A., Singer, S.J. & Wells, I. C. (1949). Sickle Cell Anaemia, a Molecular Disease. Science, 

110(2865), 543–554. Ashutosh, L. Elliott, P. & 11. Vicninsky, J. (2005). Sickle Cell Disease. In: A. Victor Haffbrand, Daniel Catovsky and Eward GD (Editors). Post Graduate Haematology, 5th edition chapter 7, 104–118. Bhagat, S., Patra, P.K. & 

Thaku, A. S. (2013). Fetal 12. haemoglobin and B–globin Gene Cluster Haplotypes Among Sickle Cell Patients in Chhattisgarh. Journal of Clinical Diagnosis Research, 7, 13. 269–272. Steinberg, M. H. (2009). Generic Etiologies for Phenotypic Diversity in Sickle Cell Anaemia. Scientific World Journal, 9, 46–67. 

14. 14. Ginder, G.D. (2015). Epigenetic Regulation of Fetal Globin Gene Expression in Adult Erythroid Cells. Translational Research, 165, 115–125. Ganong, W.E. (1997). 15. Textbook of Medical Physiology. 18th edition, Page 890. Stamford: Appleton and Lange; page 890. 

Solovieff, N., Milton, J.N., Harley, S.W., Sherva, R. & Sebastiani, P. (2010). Fetal Haemoglobin in Sickle Cell Anaemia: Genome–wide Association Studies Suggest a Regulatory Region in the 5 Olfactory Receptor Gene Clusters. Blood, 115, 1315–1822. Thein, S.I., Menzel, S., Peng, X., Best. S. & Jiang, J.(2007). Intergenic Variants of HBS1L MYB are Responsible for a Major Quantitative Trait Locus on Chromosome 69 23 Influencing Fetal Haemoglobin Level in Adult. Proceedings of the National Academy of Science USA, 104(27), 11346–11351. Bauer, D.E., Kamran, S.C., Lessard, S. & Fajiwara, Y. (2013). An Erythroid Enhancer of BCL11A Subject to Genetic Variation Determines Fetal Haemoglobin Level. Science, 342, 253–257. Vijay, G., Sanakra, U. & Stuart, H. (2013). The Switch from fetal to adult Haemoglobin. Cold Spring Herb Perspective Medicine, 3: a011643. Stamatoyannopoulos, G. (2005). Conrol of Globin Gene Expression During Development and Erythroid Differentiation. Experimental Haematology, 33:259–271. Bauer, D.E., Kamran, S.C. & Orkin, S.H. (2012). Reawakening fetal haemoglobin: prospects for new therapies for the beta globin disorders. Blood, 120(15), 2945–2953. Betke, K., Marti, H.R. & Schlicht, I. (1959). Estimation of small percentages of fetal haemoglobin. Nature, 184: 1877–1878. 

Francesio M. C, Fabio D. P., Silivia V., Fiorenzo M. & Valerio N. (2011). Human DNA Extraction Methods: Patents on DANA and Gene Squences, 5, 1–7. Gaurab, K. Restriction Fragment Length Polymorphism (RFLP): principle, procedure and application. Online Biology Notes. www. onlinebiology notes.com 2017. Öner, C., Dimovski, AJ, Olivieri, NF, et al., (1992). ßs Haplotypes in Various World Populations. Human Genetics, 89(1), 99–104. Uko, E. K., Useh, M. F. & Gwanmesia, F. N. (1997). Frequency of Foetal Haemoglobin and Haemoglobin Values in Various Haemoglobin Genotypes in Calabar, Nigeria. East African Medical Journal, 74(12), 809–811. Adekile, A., Al–Kandari, M., Haider, M., Rajaa, M., D‘Souza, M., & Sukumaran, J. (2007). Hemoglobin F Concentration as a Function of Age in Kuwaiti Sickle Cell Disease Patients. Medical Principles and Practice, 16(4): 286–290. Isah, I. Z., Udomah, F. P., Erhabor, O., Aghedo, F., Uko, E. K., Okwesili, A. N. and Adias, T. C. (2013). Foetal Haemoglobin Levels in Sickle Cell Disease (SCD) Patients in Sokoto, Nigeria. British Journal of Medical Health Science, 1(6), 36–47. Farrell, J.J., Sherva, R.M., Chen, Z.Y., et al. (2011). A 3 dp Deletion in the HBS1L MYB Intergenic Region on Chromosome 6923 is Associated with Hb F 

20. 20. 
21. 22. 

Afr J Lab Haem Trans Sci 2022, 1(2): 158 – 172 

171 

Zakariyahu & Ajayi / BCL11A and HBS1L–MYB Polymorphisms in SCA 

23. 23. 
24. 24. 
25. 25. 
26. 26. 
27. 27. 

172 

expression. Blood, 117(18), 4935-4945. 

28. 28. 

Makani, J., Menzel, S. & Nkya, S. (2010). Genetics of Fetal Haemoglobin in Tanzanian and British Patients with Sickle Cell Anaemia. Blood, 117(4), 1390-1392. Sankaran, V.G., Menne, T.F. and Scepanovic, D. (2011). MicroRNA–15a and -16-1 act via MYB to Elevate Fetal Haemoglobin Expression in Human Trisomy 13. Proceedings of National Academy of Science US A, 108(4), 1519-1524. Bhanushali, A.A, Patra, P.K., Nair, D., Verma, H. & Das, B.R. (2015). Genetic Variant in the BCL11A (rs1427407), but not HBS1–MYB (rs6934903) Loci Associate with Fetal Hemoglobin Levels in Indian Sickle Cell Disease Patients. Blood Cells, Molecules, and Diseases, 54(1), 4-8. Hassan, F.M. & Al–Zahrani, F.M. (2019). BCL11A rs1427407 Genotypes in Sickle Cell Anemia Patients Undergoing Stroke Problems in Sudan. Korean Journal of Family Medicine, 40(1): 53-64. Jiang, B.Y., Zhang, X.C. & Su, 32. J. (2013). BCL11A Overexpression Predicts Survival and Relapse in Non small Cell Lung Cancer and is Modulated by microRNA–30a and Gene Amplification. 

29. 29. 
30. 30. 
31. 31. 

Molecular Cancer, 12(1): 1-13. Zhang, N., Jiang, B. Y., Zhang, X. C., Xie, Z., Su, J., Zhang, Q. 33. & Wu, Y. L. (2015). The BCL11A–XL Expression. Predicts Relapse in Squamous Cell Carcinoma and Large Cell Carcinoma. Journal of thoracic disease, 7(9), 1630 1634. 

Funnell, A.P., Prontera, P., Ottaviani, V. et. al. (2015). 2p15–p16.1 Microdeletion Encompassing and Proximal to BCL11A are Associated with Elevated Hb F in Addition to Neurologic Impairment. Blood, 126, 

89-93. 

Sankaran, V. G., Menne, T. F., Xu, J., Akie, T. E., Lettre, G. (2008). Van Handel, B. and Orkin, S. H. Human Fetal Hemoglobin Expression is Regulated by the Developmental Stage–Specific Repressor BCL11A. Science, 322(5909), 1839-1842. Jiang, J., Best, S., Menzel, S. et. al. (2006). cMYB is Involved in the Regulation of Fetal Hemoglobin Production in Adults. Blood, 108(3), 1077 1083. 

Nakamura, T., Yamazaki, Y., Saiki, Y. et. al. (2000). Evi9 Encodes a Novel Zinc Finger Protein that Physically Interacts with BCL6, a Known Human B–cell Proto oncogene Product. Molecular 

34. 34. 
35. 35. 
36. 36. 

and Cellular Biology, 20(9), 

3178-3186. 

Olaniyi, J.A., Arinola, O.G. & Odetunde, A.B. (2010). Foetal Haemoglobin (Hb F) Status of Adult Sickle Cell Anaemia Patients in Ibadan, Nigeria. Annals of Ibadan Postgraduate Medicine, 8(1), 30-33. 

Tshilolo, L., Summa, C. & Grgori, C. (2012). Foetal Haemoglobin, Erythrocytes Containing Foetal Haemoglobin and Haematological Features in Congolese Patients with Sickle Cell Anaemia. Anaemia, Article ID 105349,7 pages. Sedgewick A. E, Timofeev N. & Sebastinni P. (2008). BCL11A is a Major Hb F Quantitative Trait Locus in Three Different Population with 

B – 

Haemoglobinopathies. Blood Cell Molecular Diseases, 41(3), 255-258. 

Close, J., Game, L., Clark, B., Bergounioux, J., Gerovassili, A. P. & Thein, S.L. (2004). Genome Annotation of a 1.5 Mb Region of Human Chromosome 6q23 Encompassing a Quantitative Trait Locus for Fetal Haemoglobin Expression in Adults. BioMedical Central Genomics, 5(1), 33-37. 

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