Common Genetic Variants of Fetal Hemoglobin Modify Hematological Phenotypes in MDS/MPN/Myeloma Patients Receiving Cytotoxic Drugs

Original Research

Ann Hematol Oncol. 2022; 9(4): 1403.

Common Genetic Variants of Fetal Hemoglobin Modify Hematological Phenotypes in MDS/MPN/Myeloma Patients Receiving Cytotoxic Drugs

Igbineweka NE1,2,3,4, Pilarski A1,2, Rooks H3, Breton A3, Hall H1, Joshi D1, Meeks D1,2,4, Chevassut TJ1,2, Thein SL4 and Menzel S3*

1Brighton & Sussex Medical School, University of Sussex, UK

2Department of Haematology, Brighton & Sussex University Hospitals NHS Trust, UK

3Molecular Haematology, School of Cancer and Pharmaceutical Sciences, The Rayne Institute, King’s College London, UK

4Sickle Cell Branch, National Heart, Lung and Blood Institute, National Institute of Health, USA

*Corresponding author: Stephan Menzel, School of Cancer and Pharmaceutical Sciences, The Rayne Institute King’s College London, 123 Coldharbour Lane, London SE5 9NU, UK

Received: August 26, 2022; Accepted: September 15, 2022; Published: September 22, 2022


Genetic studies identify common variants within the HBS1L-MYB intergenic region (HMIP), BCL11A, and Xmn1-HBG2 as associated with elevated fetal hemoglobin (HbF) levels and other clinically important human hematological traits. Recent studies suggest HbF is a predictor of outcome in MDS/AML patients receiving decitabine. We assessed effects of HbF genetic variants on hematological traits in Myeloproliferative Neoplasm (MPN), Myelodysplastic Syndrome (MDS) and myeloma on HbF-inducing therapy to determine potential for variants predicting treatment response. Seven common HbF variants at HMIP, BCL11A, Xmn1-HGB2 loci were genotyped in 89 patients with MPN on Hydroxyurea (HU), myeloma on Lenalidomide, and MDS on Azacytidine. HbF genetic association was seen with rs9494142 (HMIP) in MPN on HU (p = 0.04) and rs1427407 (BCL11A) in myeloma on Lenalidomide (p = 0.002). HMIP variants rs9494142 and rs6920211 influenced baseline platelets (p = 0.04) and hemoglobin treatment response (p = 0.02). rs1427407 (BCL11A) was significantly associated with increased platelets (p = 0.04) negating thrombocytopenic tendency of Lenalidomide. These HbF variants showed significantly discordant minor allele frequencies in MDS/MPN/myeloma compared to wider European population data. This small study finding together suggest the implication of these variants in treatment response and disease biology in MDS/MPN/myeloma warranting larger prospective genotype-phenotype association studies.


• HbF genetic variants influence HbF and other hematological traits in MPN, myeloma and MDS patients at baseline and response to HbF-inducing cytotoxic therapy.

• Frequencies of minor alleles of HBS1L-MYB and BCL11A are significantly discordant compared with wider population genomic data suggesting a pathobiological role of these loci in MPN, myeloma and MDS.


Fetal hemoglobin, although the predominant hemoglobin until birth, continues to be synthesized in minimal amounts throughout adult life. [1] Some reactivation of fetal hemoglobin (HbF, alpha2 gamma2) in adults can occur in certain hematopoietic states such as Myelodysplastic Syndrome (MDS), Myeloproliferative Disorders (MDS), and Sickle Cell Disease (SCD); sometimes as a response to therapy, but occasionally prior to any intervention. [2] The significance of elevated HbF levels for patients towards the understanding of disease mechanisms is so far unclear. It is conceivable that HbF could be a marker for imbalanced or clonal hematopoiesis, or, alternatively, for committed pathways of the hematopoietic system to cope with disease. It could be a sign of effective therapeutic intervention or represent stress inflicted on the bone marrow by therapy. [1] In some cases, higher HbF levels could have been present before the onset of disease, but the causes of this could have influenced risk for the development of manifest disease, or impacted disease progression. [4,5] While HbF can just be a reaction to disease or therapy, there is also the possibility that hematopoietic processes leading to increased HbF are part of the pathogenetic process itself, influencing disease risk, progression or treatment efficacy. It appears beneficial to dissect these possible relationships between increased HbF levels and certain hematopoetic disease states, since HbF levels could indeed have diagnostic or prognostic value, or understanding its causes could help to understand disease itself. Lübbert et al. [4] suggested recently that baseline HbF had prognostic value in predicting outcome in MDS/ AML patients receiving decitabine, but genetic variants associated with HbF were not evaluated which could have provided insight for genetic prediction of treatment response and prognosis.

HbF has high heritability, and like other hematological traits, is tightly genetically regulated. [6-9] HbF genetic regulation has been well delineated in hemoglobinopathies and inherited bone marrow failure syndromes. [10] Three Quantitative Trait Loci (QTL) accounts for 20-50% of HbF common variation - HBS1L-MYB intergenic polymorphism (HMIP) on chromosome 6q11, BCL11A on chromosome 2p [12] and Xmn1-HBG2 (rs7482144) on the β-globin cluster on chromosome 11p [13]. HbF variants such as HMIP and BCL11A have also been shown to regulate other hematological traits. [14-16] In addition, BCL11A and Xmn1-HBG2 (rs7482144) has been suggested to influence HbF response to hydroxyurea (HU) in the β-hemoglobinopathies. [17] Nevertheless, there remains a paucity of data describing significance of HbF variants amongst hematological malignancies.

This study investigates HbF regulatory potential variant modifier effects and prevalence amongst patients with MPN/myeloma/MDS on cytotoxic therapy; agents which are also used for HbF therapeutic reactivation in SCD and beta-thalassemia. [18-21] HbF response to these chemotherapy agents are likely to be highly variable and genetically influenced reflecting alterations of hematological kinetics and improvement of blood counts. Delineation of these HbF variants, could allow for added insight to disease risk and expression, molecular characterization, and prediction of response to these chemotherapy agents in MPN/Myeloma/MDS.


Subject group

Eighty-nine patients, 44 with MPN (World Health Organization (WHO) classification 2008) on HU; 33 patients with Myeloma (International Myeloma Working Group 2003) on Lenalidomide; and 12 patients with MDS (WHO classification 2001) on Azacytidine (AZA) were recruited from hematology clinics at Brighton & Sussex University Hospitals (BSUH) NHS Trust, UK (supplemental data (S) Figure S1). Four out of the 12 patients with MDS, had secondary AML at the time of measurement. A subset of patients (N = 16) (7 MPN, 6 myeloma and 3 MDS patients) had baseline values before starting therapy and had repeat values 4 weeks and 3-months after cytotoxic agent initiation. All patients gave written consent. The study was approved by local and national UK NHS Research Ethics Committee (REC) (reference 14/WA/1078).

Blood Sampling & Genotyping

Two EDTA blood samples were collected from each patient, one processed at BSUH pathology for HbF using HPLC (BioRad variant) and the other processed for hematological parameters (Sysmex XN- 9000 automated hematology analyzers) (Norderstedt, Germany). Elevated HbF was defined as ≥ 1%.

DNA was extracted from peripheral blood leukocytes from the second EDTA sample and genotyped for 7 HbF variants - rs6545816 and rs1427407 (BCL11A), rs9494142, rs6920211, rs9494145, and rs66650371 (HMIP), and rs748214 using Taqman procedure (standard assay system and MGB probes from Thermo Fisher/ Applied Biosystems, Foster City, CA).

Statistical Analysis

Genetic association of blood traits was performed with linear regression (IBM SPSS Statistics 24 & GraphPad software, La Jolla, CA, USA) using a genotypic genetic model adjusting for age and sex as covariates due to HbF levels being lower with increasing age and higher levels observed in females compared to males. Analysis of variance was performed to determine genotype effect against mean HbF/hematological parameters. Hardy-Weinberg test was performed on all genotype results for quality assurance. No genotype was found to deviate from the Hardy-Weinberg equilibrium. Hematological parameters which did not satisfy assumptions of normality were logtransformed. Statistical significance was determined as a p-value of < 0.05 with Bonferroni-adjustment for multiple testing.


Fetal Hemoglobin Is Variably Expressed In MPN/Myeloma/ MDS at Baseline (Pre-Cytotoxic Treatment) and On Induction (Post-Cytotoxic Treatment)

We studied general blood parameters, HbF levels, and genetic HbF modifiers in 89 patients with hematological malignancy (MPN, Myeloma and MDS, Table 1) in relation to HbF-inducing cytotoxic therapy and genetic modifiers of HbF expression. In 16 of the 84 patients – 7 MPN, 6 myeloma and 3 MDS – we were able to compare baseline values before starting therapy with values obtained 4 weeks and 3 months after cytotoxic agent initiation. Mean baseline HbF for this total group was 0.78% (Table 1) with 0.73%, 0.70%, 0.95% for MPN, Myeloma and MDS respectively (Table S1). Four patients had elevated baseline HbF (2 MPN, 1 Myeloma and 1 MDS) with maximal elevated baseline HbF level of 1.2% seen in two patients (1 MPN, 1 MDS). Mean induced HbF levels were 1.06%, 0.77%, and 2.36% in MPN on HU, Myeloma on Lenalidomide and MDS on AZA groups respectively. Mean induced HbF levels for the total hematological malignancy group (MPN/myeloma/MDS) was 1.08%. Elevated HbF was prevalent amongst 28.6% MPN on HU, 19% Myeloma on Lenalidomide and 63.6% MDS on AZA groups.