Hb Grand Junction (HBB: c.348_349delinsG; p.His117IlefsX42): a new hyperunstable hemoglobin variant

Hyperunstable hemoglobinopathy (HUH) [dominantly inherited β-thalassemia (β-thal)] is a relatively rare form of congenital hemolytic anemia in which mutations occur in the genes encoding for α and β chains, or both chains of the hemoglobin (Hb) molecule. We describe two Hispanic adolescents with a new unstable Hb variant (HBB: c.348_349delinsG; p.His117IlefsX42), resulting from a frameshift mutation at codons 115/116 of the β-globin gene. Both patients also have a 3.7 kb deletion on one α gene, leading to a decreased imbalance between α and β chain formation, and subsequently a milder phenotype than that seen in other hyperunstable Hb variants.

Temporal sequence of major biochemical events during blood bank storage of packed red blood cells

BACKGROUND

We used sensitive spectroscopic techniques to measure changes in Band 3 oligomeric state during storage of packed red blood cells (RBC); these changes were compared to metabolic changes, RBC morphology, cholesterol and membrane protein loss, phospholipid reorganisation of the RBC membrane, and peroxidation of membrane lipid. The aim of the study was to temporally sequence major biochemical events occurring during cold storage, in order to determine which changes may underlie the structural defects in stored RBC.

MATERIALS AND METHODS

Fifteen RBC units were collected from normal volunteers and stored under standard blood bank conditions; both metabolic changes and lipid parameters were measured by multiple novel assays including a new mass spectrometric measurement of isoprostane (lipid peroxidation) and flow cytometric assessment of CD47 expression. Band 3 oligomeric state was assessed by time-resolved phosphorescence anisotropy, and RBC morphology by microscopy of glutaraldehyde-fixed RBC.

RESULTS

Extracellular pH decreased and extracellular potassium increased rapidly during cold storage. Band 3 on the RBC membrane aggregated into large oligomers early in the storage period and coincident with changes in RBC morphology. Membrane lipid changes, including loss of unesterified cholesterol, lipid peroxidation and expression of CD47, also changed early during the storage period. In contrast loss of acetylcholinesterase activity and haemolysis of RBC occurred late during storage.

DISCUSSION

Our results demonstrate that changes in the macromolecular organisation of membrane proteins on the RBC occur early in storage and suggest that lipid peroxidation and/or oxidative damage to the membrane are responsible for irreversible morphological changes and loss of function during red cell storage.

An assessment of the usefulness of immunohistochemical stains in the diagnosis of hairy cell leukemia

Annexin-1 and T-bet are recently described immunohistochemical stains that reportedly assist in the diagnosis of hairy cell leukemia (HCL). Our objective was to assess the sensitivity and specificity of a panel of immunohistochemical stains in distinguishing HCL from other B-cell neoplasms, particularly splenic and extranodal marginal zone lymphomas (SMZL and ENMZL, respectively). The study included 234 bone marrow biopsy specimens: 101 HCL, 13 SMZL, and 10 ENMZL cases were assessed with CD20, tartrate-resistant acid phosphatase (TRAP), DBA.44, a-1, T-bet, and cyclin D1, and 110 control cases were assessed with annexin-1 and T-bet. Our study showed that annexin-1 is a specific and sensitive marker for HCL; however, interpretation is limited by positivity within myeloid precursors. T-bet, DBA.44, and TRAP immunohistochemical stains lack sufficient sensitivity and specificity to differentiate HCL from either form of marginal zone lymphoma. However, our data suggest that the addition cyclin D1 to the immunostaining panel will increase the sensitivity and specificity of HCL diagnosis.

Hb Lake Tapawingo [α46(CE4)Phe→Ser; HBA2:c.140T>C]: a new unstable α chain hemoglobin variant associated with low systemic arterial saturation

A new unstable α-globin variant was detected in a child with hypoxemia and anemia. The child's mother was found to carry the same mutation. The hemoglobin (Hb) variant co-eluted with Hb A(2) by cation exchange high performance liquid chromatography (HPLC) and appeared cathodal to Hb A and anodal to Hb F by isoelectric focusing. It represented less than 20% of the total Hb and was unstable by isopropanol testing. Gene sequencing identified a missense mutation on the α2 gene [HBA2:c.140T>C]. Oxygen dissociation and P(50) test results were normal.

Hb Nebraska [β86(F2)Ala→Ile (HBB:c.259G>A;260C>T)]: a unique high oxygen affinity hemoglobin variant with a double nucleotide substitution within the same codon

A new high oxygen affinity hemoglobin (Hb) variant, Hb Nebraska [β86(F2)Ala→Ile, GCC>ATC; HGVS: HBB: c.259G>A;260C>T] is reported. This variant was not identified by routine methods and was only suspected due to erythrocytosis and an abnormal p50 value. The variant was analyzed by DNA sequencing and mass spectrometry (MS). The β chain variant is unusual in that it has two nucleotide substitutions occurring at the same codon.

Isolated del(5q) in myeloid malignancies: clinicopathologic and molecular features in 143 consecutive patients

World Health Organization (WHO) criteria were used to identify 143 consecutive patients (median age 73 years; 90 females) with myeloid neoplasms and isolated del(5q) seen between 1989 and 2009. We have previously reported on 88 (61%) of these patients who met criteria for WHO defined "myelodysplastic syndromes (MDS) with isolated del(5q)." The remaining 55 patients were classified as having "other" MDS variants (n = 29; 20%), acute myeloid leukemia (AML; n = 14; 10%), or myeloproliferative neoplasms (MPN; n = 12; 8%). DNA was available in 138 patients and mutation screening revealed 20 cases with JAK2, 6 with IDH, and 3 with MPL mutations; JAK2 and MPL mutations were seen mostly in MPN or "MDS with isolated del(5q)" whereas IDH mutations were frequent in other MDS variants. Overall median survival for the 143 patient cohort was 35 months and leukemic transformation (LT) was documented in 19 (~13%) cases. "MDS with isolated del(5q)" had the best prognosis with median survival of 66 months and LT rate of ~6%. Survival was poor among the other myeloid neoplasm subgroups regardless of specific morphologic diagnosis. Multivariable analysis identified higher leukocyte count and percentage of bone marrow and circulating blasts as independent predictors of shortened survival. The first two parameters and the presence of IDH mutations predicted inferior leukemia-free survival. The current study validates the prognostic relevance of considering "MDS with isolated del(5q)" as a separate WHO subcategory and identifies leukocytosis, higher blast count, and IDH mutations as being prognostically detrimental, in myeloid neoplasms associated with isolated del(5q).

Hemoglobin Raleigh results in factitiously low hemoglobin A1c when evaluated via immunoassay analyzer

BACKGROUND

Glycosylated hemoglobin (HbA1c) is commonly used to assess long-term blood glucose control in patients with diabetes mellitus. Numerous conditions including hemoglobinopathies can alter HbA1c measurements and cause misleading results.

OBJECTIVE

To report a 13-year-old male with Type 1 diabetes mellitus who had low HbA1c measurements, despite persistent hyperglycemia.

DESIGN/METHODS

HbA1c was initially measured by immunoassay. Hb electrophoresis was then employed to assess potential Hb variants. Electrospray ionization (ESI) tandem mass spectrometry of isolated Hb and gene sequencing of the Hbβ gene were used to specifically identify the Hb variant.

RESULTS

HbA1c measurement by immunoassay revealed an unusually low HbA1c of 3.9%. Hb electrophoresis revealed an aberrant Hb. The ESI mass spectrum of the intact Hb sample revealed a variant β-chain of 15,881 Da, 14 Da heavier than the mass of the normal Hb β-chain (15,867 Da). Sequence analysis of the 965.45 Da peptide suggested a substitution of valine (Val) to acetylated alanine (Ala). The DNA sequence of the patient's Hbβ gene revealed a single-base heterozygous mutation (GTG to GCG) at Base 2 of the codon of the first amino acid, producing a Val→Ala substitution, previously termed Hb-Raleigh. Because the acetylated N-terminal amino acid of the Hb-Raleigh β chain cannot be glycated, the HbA1c immunoassay will result in falsely low HbA1c levels.

CONCLUSION

In managing diabetic patients, knowledge of hemoglobinopathies influencing HbA1c determination methods is essential because hemoglobin variants may cause mismanagement of diabetes. Unusual results should prompt further analysis for a hemoglobinopathy as the potential cause of aberrant results.

Bone marrow morphologic features in polycythemia vera with JAK2 exon 12 mutations

The diagnosis of polycythemia vera (PV) requires the integration of clinical and laboratory findings, bone marrow morphologic features, and JAK2 analysis. JAK2(V617F) (exon 14) mutation is found in 95% of PV cases. Functionally similar mutations in JAK2 exon 12 have also been described, but a thorough bone marrow study has not been done. We identified 7 PV cases with exon 12 mutations; all had hypercellular bone marrow with erythroid hyperplasia. Small, atypical megakaryocytes predominated; atypical megakaryocyte lobation and abnormal chromatin distribution was identified in all cases. Rare clusters of megakaryocytes could be found but were typically subtle. Because JAK2 exon 12-positive PV cases lack the classic myeloproliferative morphologic features, bone marrow samples from the patients may be difficult to classify as myeloproliferative neoplasms. Clinically suspected PV with low serum erythropoietin and absent JAK2(V617F), together with the bone marrow findings of erythroid hyperplasia and subtle megakaryocytic atypia, should prompt an evaluation for an exon 12 mutation.

Autoimmune cytopenia in chronic lymphocytic leukemia/small lymphocytic lymphoma: changes in clinical presentation and prognosis

Improved medical care could have altered the clinical presentation and survival of patients with chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) complicated by autoimmune disease cytopenia (AID cytopenia). We reviewed the clinical characteristics, treatment, and outcome of AID cytopenia that was diagnosed in 75 (4.3%) of 1750 patients with CLL seen at a single institution over 10 years. When compared with the historical reported data, our study shows a lower rate of autoimmune hemolytic anemia (2.3%), and similar rates of immune thrombocytopenia (2.0%), and pure red blood cell aplasia (0.5%). AID cytopenia occurred at all stages of CLL, responded well to treatment, did not alter overall survival, and contributed to death in only 6 (12%) patients. We propose that more sensitive and accurate diagnostic methods for CLL have decreased the perceived prevalence of AID cytopenia and that improvements in management could have increased the survival of these patients.

TheJAK2V617F Mutation is Absent in Patients with Erythrocytosis Due to High Oxygen Affinity Hemoglobin Variants

High oxygen affinity hemoglobin (Hb) variants are an important and well characterized cause of secondary erythrocytosis. We tested 22 patients with high oxygen affinity beta chain variants for the presence of the JAK2 V617F mutation that has been reported in chronic myeloproliferative disorders, particularly polycythemia vera. All specimens showed the absence of this mutation. This observation contributes to the overall clinical specificity of the JAK2 V617F mutation.

Two Unstable β Chain Variants Associated with β-Thalassemia: Hb Miami [β116(G18)His→Pro], and Hb Hershey [β70(E14)Ala→Gly], and a Second Unstable Hb Variant at β70: Hb Abington [β70(E14)Ala→Pro]

We report on three previously undescribed unstable hemoglobin (Hb) variants: Hb Miami, Hb Hershey and Hb Abington. Hb Miami was associated with a beta(+)-thalassemia (thal) mutation [IVS-I-110 (G-->A)], whereas Hb Hershey was associated with a B0-thal mutation [IVS-I-1 (G-->A)]. Hb Hershey also has decreased oxygen affinity. These three Hb variants illustrate the range of clinical severity that can be seen with unstable Hb variants, particularly when combined with a thalassemic mutation.

Quintuple α-Globin Gene: A Novel Allele in a Sudanese Man

Multiple alpha-globin repeats have previously been discovered in humans and other mammals. A quintuple alpha-globin gene (alphaalpha/alphaalphaalphaalphaalpha) was found in a Sudanese male undergoing evaluation for microcytosis.

Changes in Band 3 oligomeric state precede cell membrane phospholipid loss during blood bank storage of red blood cells

BACKGROUND

Lipid loss in the form of vesicles contributes to the red blood cell (RBC) storage lesion, and this loss of lipid is correlated with changes in membrane protein function. Sensitive spectroscopic techniques were used to measure changes in Band 3 oligomeric state during storage of RBCs, compared to metabolic changes and phospholipid loss. The aim of the study was to determine whether changes in the macromolecular organization of membrane proteins occur before, coincident with, or after lipid loss during RBC storage.

STUDY DESIGN AND METHODS

Five RBC units were collected from normal volunteers and stored under standard blood bank conditions, and both metabolic changes and lipid loss were measured by multiple assays. Band 3 oligomeric state was assessed by time-resolved phosphorescence anisotropy and fluorescence resonance energy transfer of eosin-5-maleimide-labeled RBC ghosts.

RESULTS

Extracellular pH decreased and extracellular potassium increased rapidly during cold storage of blood. Band 3 on the RBC membrane exhibited a shift from small to large oligomers early in the storage period and before detectable loss of phospholipid from the RBC membrane. The immobilized fraction of Band 3, that which is tethered to the cytoskeletal network via spectrin and ankyrin, did not change during cold storage.

CONCLUSION

Our results demonstrate that changes in the macromolecular organization of membrane proteins on the RBC occur early in storage, and these changes may induce phospholipid loss, irreversible morphologic changes, and loss of function during RBC storage.

Percentage of smudge cells on routine blood smear predicts survival in chronic lymphocytic leukemia

PURPOSE

Smudge cells are ruptured chronic lymphocytic leukemia (CLL) cells appearing on the blood smears of CLL patients. Our recent findings suggest that the number of smudge cells may have important biologic correlations rather than being only an artifact of slide preparation. In this study, we evaluated whether the smudge cell percentage on a blood smear predicted survival of CLL patients.

PATIENTS AND METHODS

We calculated smudge cell percentages (ratio of smudged to intact cells plus smudged lymphocytes) on archived blood smears from a cohort of previously untreated patients with predominantly early-stage CLL enrolled onto a prospective observational study. The relationship between percentage of smudge cells, patient survival, and other prognostic factors was explored.

RESULTS

Between 1994 and 2002, 108 patients were enrolled onto the study and had archived blood smears available for review; 80% of patients had Rai stage 0 or I disease. The median smudge cell percentage was 28% (range, 1% to 75%). The percentage of smudge cells was lower in CD38(+) versus CD38(-) patients (P = .019) and in Zap70-positive versus Zap70-negative patients (P = .028). Smudge cell percentage as a continuous variable was associated with prolonged survival (P = .042). The 10-year survival rate was 50% for patients with 30% or less smudge cells compared with 80% for patients with more than 30% of smudge cells (P = .015). In multivariate analysis, the percentage of smudge cells was an independent predictor of overall survival.

CONCLUSION

Percentage of smudge cells on blood smear is readily available and an independent factor predicting overall survival in CLL.

Relative red blood cell enzyme levels as a clue to the diagnosis of pyruvate kinase deficiency

Evaluation of two patients with transfusion dependent anemia revealed RBC pyruvate kinase to be 33% and 41% of the mean normal value, with normal or high values of other RBC enzymes. Parental PK activities were just below normal in three of four of the parents. Subsequent DNA analysis revealed both patients to be compound heterozygotes for PKLR gene mutations, two of which are previously undescribed. Borderline low pyruvate kinase activities with increased in other RBC enzyme activities should prompt consideration of measurement of parental enzyme activities, and confirmation by DNA analysis if available.

Five variants of the beta-globin gene without clinical or hematological effects: Hb Maryland [beta 47(CD6)Asp-->His], Hb Kent [beta 37(C3)Trp-->Cys], Hb Visayan [beta 136(H14)Gly-->Cys], Hb Cutlerville [beta 138(H16)Ala-->Val] and Hb Hornchurch [beta 43(CD2)Glu-->Lys]

We report on five hemoglobin (Hb) beta chain variants that were initially identified either by electrophoretic, chromatographic or isoelectric focusing (IEF) methods. These variants do not appear to be associated with clinical or hematological abnormalities. All variants were confirmed by DNA sequence analysis.