Increased HbF levels in dyserythropoiesis

Lessons From Pediatric MDS: Approaches to Germline Predisposition to Hematologic Malignancies

Pediatric myelodysplastic syndromes (MDS) often raise concern for an underlying germline predisposition to hematologic malignancies, referred to as germline predisposition herein. With the availability of genetic testing, it is now clear that syndromic features may be lacking in patients with germline predisposition. Many genetic lesions underlying germline predisposition may also be mutated somatically in de novo MDS and leukemias, making it critical to distinguish their germline origin. The verification of a suspected germline predisposition informs therapeutic considerations, guides monitoring pre- and post-treatment, and allows for family counseling. Presentation of MDS due to germline predisposition is not limited to children and spans a wide age range. In fact, the risk of MDS may increase with age in many germline predisposition conditions and can present in adults who lack classical stigmata in their childhood. Furthermore, germline predisposition associated with DDX41 mutations presents with older adult-onset MDS. Although a higher proportion of pediatric patients with MDS will have a germline predisposition, the greater number of MDS diagnoses in adult patients may result in a larger overall number of those with an underlying germline predisposition. In this review, we present a framework for the evaluation of germline predisposition to MDS across all ages. We discuss characteristics of personal and family history, clinical exam and laboratory findings, and integration of genetic sequencing results to assist in the diagnostic evaluation. We address the implications of a diagnosis of germline predisposition for the individual, for their care after MDS therapy, and for family members. Studies on MDS with germline predisposition have provided unique insights into the pathogenesis of hematologic malignancies and mechanisms of somatic genetic rescue vs. disease progression. Increasing recognition in adult patients will inform medical management and may provide potential opportunities for the prevention or interception of malignancy.

Diagnostic work-up for severe aplastic anemia in children: Consensus of the North American Pediatric Aplastic Anemia Consortium

The North American Pediatric Aplastic Anemia Consortium (NAPAAC) is a group of pediatric hematologist-oncologists, hematopathologists, and bone marrow transplant physicians from 46 institutions in North America with interest and expertise in aplastic anemia, inherited bone marrow failure syndromes, and myelodysplastic syndromes. The NAPAAC Bone Marrow Failure Diagnosis and Care Guidelines Working Group was established with the charge of harmonizing the approach to the diagnostic workup of aplastic anemia in an effort to standardize best practices in the field. This document outlines the rationale for initial evaluations in pediatric patients presenting with signs and symptoms concerning for severe aplastic anemia.

Influences of genetic variation on fetal hemoglobin

Fetal hemoglobin (HbF) plays a dominant role in ameliorating morbidity and mortality of hemoglobinopathies. The authors performed a replicated study following the genome-wide association study (GWAS) guidelines to identify the genetic mechanics that influence HbF. The authors recruited and phenotyped 312 unrelated β-thalassemia subjects. Single-nucleotide polymorphism (SNP) analysis was performed by using polymerase chain reaction (PCR)/restriction enzymes. Four independent regions of interest were identified: HBS1L-MYB intergenic region, BCL11A locus, β-globin gene cluster, and the CSNK2A1 gene. There were 10 SNPs associated with HbF levels. In addition, haplotypes of HBS1L-MYB and BCL11A were identified and showed association with HbF production. Three independent regions, including HBS1L-MYB intergenic region, BCL11A locus, and β-globin gene cluster, were associated with HbF levels. This study can significantly improve the GWAS findings in Chinese cohorts and is useful for further research in the field of common predictors of the erythropoiesis.

XmnI polymorphism is associated with fetal hemoglobin levels in hypoplastic syndromes

CONTEXT AND OBJECTIVE

Acquired fetal hemoglobin (HbF) elevation has been implicated as a prognostic factor in dyserythropoietic disorders. Our objectives were to examine acquired HbF increases in aplastic anemia (AA) and paroxysmal nocturnal hemoglobinuria (PNH) patients, and to evaluate whether there is an association between the presence of XmnI and 5' hypersensitive site locus control region (LCR-HS2) polymorphisms and the HbF levels.

DESIGN AND SETTING

Cross-sectional study at the Hematology and Blood Transfusion Service of Universidade Federal de São Paulo - Escola Paulista de Medicina.

METHODS

We studied a group of 37 patients with AA and/or PNH. Polymerase chain reaction (PCR) and enzymatic digestion were utilized to analyze XmnI polymorphisms; and PCR, cloning and automated sequencing for the HS2 polymorphisms.

RESULTS

The mean HbF level was 2.32%, but there was no significant difference in HbF level between the AA and PNH groups (p = 0.46). HbF levels of less than 1.0% showed a significant correlation with absence of the XmnI (+) polymorphism (p = 0.02). The presence of the XmnI allele was greater in the AA group (p = 0.007).

CONCLUSIONS

XmnI polymorphism absence reduction is associated with acquired HbF elevation. Further studies are required to confirm these observations and make treatment, prognosis and survival comparisons.

Acquired hemoglobin H disease in a patient with aplastic anemia evolving into acute myeloid leukemia

CONTEXT

The prognosis of severe aplastic anemia has improved since the introduction of bone marrow transplantation and treatment with antithymocyte globulin. In contrast to the success of these protocols, studies with long term follow-up have shown the occurrence of clonal diseases such as paroxysmal nocturnal hemoglobinuria, myelodysplastic syndrome and acute leukemia in aplastic anemia.

CASE REPORT

We report the first case of a Brazilian patient with aplastic anemia who developed myelodysplastic syndrome and acute myeloid leukemia showing acquired hemoglobin H and increased fetal hemoglobin.

Significance of fetal hemoglobin-containing erythroblasts (F blasts) and the F blast/F cell ratio in myelodysplastic syndromes

To investigate the relationship between the fetal hemoglobin-containing erythroblasts (F blasts) and apoptosis in myelodysplastic syndromes (MDS), we immunohistochemically assessed F blasts, F cells, and apoptosis in 137 patients with MDS. A marked increase in the number of F blasts in the bone marrow was identified in 116 of 137 patients (84.7%), and the number of F cells was elevated in 54 patients (39.4%). Among the erythroblasts stained by anti-glycophorin C antibody, the mean percentage of F blasts was 14.63 +/- 9.17% in MDS, which was significantly higher than that in non-MDS patients with stress erythropoiesis (4.82 +/- 3.35%, P < 0.01), although there were no significant differences in the number of F cells between these groups. In particular, 62 of the 137 MDS patients (45.3%) had an apparent increase in F blasts but no elevation of F cells. The apoptotic rate was significantly higher in the patients with a F blast/F cell (Fb/Fc) ratio >or=5.0 than in those with a Fb/Fc ratio <1.0 (P < 0.01). The results indicate that F cell precursors are incapable of maturing into functioning end-stage F cells, presumably owing to apoptotic cell death. The measurement of F blasts in the bone marrow is needed for the precise evaluation of fetal-type erythropoiesis in MDS.