Atypical Hemoglobin H Disease Due to Compound Heterozygosity for -α3.7 and --SEA Deletions and Heterozygosity for the β-Chain Variant Hemoglobin Raleigh (β1 VAL→ALA).

Abstract The co-existence of Hemoglobin H (Hb H) disease and heterozygosity for β-chain structural variants is a rare occurrence. Hb H disease has been reported in conjunction with Hb E, Hb C, Hb S, and Hb Hamilton. The combination of Hb H disease with Hb C and Hb S reportedly results in a mild hemolytic anemia without detectable Hb H. We present a new case of atypical Hb H disease that was also heterozygous for the rare β-chain variant Hb Raleigh. The patient is a 27-year-old Cambodian female referred for the evaluation of microcytic anemia unresponsive to iron. She had a lifelong history of generalized fatigue, exertional dyspnea, and weakness in her legs. Physical exam was unremarkable except for pallor of mucuous membranes. There was no hepatosplenomegaly. She had a Hb of 9.7, HCT 30.8, MCV 56, MCH 17.6, MCHC 31.5, ferritin 92. Hb analysis on IEF revealed Hb A, Hb A2, and an abnormal band slightly more anodic to Hb A. No Hb H was observed. On cation exchange HPLC, she had 49.7% Hb A, 48.1% Hb X, and 2.2% Hb A2. Reverse phase HPLC revealed a βx chain eluting immediately before βA. Oxygen affinity was slightly reduced. PCR amplification and sequencing of the β-globin gene revealed heterozygosity for Hb Raleigh (Exon 1, codon 1, GTG→GCG, VAL→ALA). The patient was also found to be a compound heterozygote for -α3.7 and --SEA deletions. This case represents a novel interaction of a structural β-chain variant with Hb H disease. Hb Raleigh has previously been reported in Caucasians and in two Swedish families. It has decreased oxygen affinity. This is the first report of this variant in a Cambodian population. The absence of any detectable Hb H likely results from the inability of variant β-chains to form a viable tetramer with a resultant decrease in βA. The low oxygen affinity did not negatively impact on the degree of anemia. This case, like some others reported previously, shows that the accurate diagnosis of Hb H disease in association with structural β-chain variants can be established by molecular methods, and the detection of Hb H on electrophoretic and chromatographic analyses may not always be reliable.

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Hb Grove City [β38(C4)Thr→Ser, ACC>AGC;HBB: c.116C>G]: A New Low Oxygen Affinity β Chain Variant

Hemoglobin ◽

10.3109/03630269.2013.789794 ◽

2013 ◽

Vol 37 (4) ◽

pp. 396-403 ◽

Cited By ~ 3

Author(s):

Rachel M. Taliercio ◽

Rendell W. Ashton ◽

Leonard Horwitz ◽

Kenneth C. Swanson ◽

Patricia C. Wendt ◽

...

Keyword(s):

Oxygen Affinity ◽

Low Oxygen ◽

Grove City ◽

Β Chain ◽

Chain Variant ◽

Low Oxygen Affinity

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The Occurrence of Four Globin Abnormalities in One Individual: Hb SC Disease with Hb Chicago and Deletional Alpha Thalassemia.

Blood ◽

10.1182/blood.v110.11.3802.3802 ◽

2007 ◽

Vol 110 (11) ◽

pp. 3802-3802

Author(s):

Heather Hughes ◽

Ferdane Kutlar ◽

Kathleen M. McKie ◽

Leslie Holley ◽

Dedrey Elam ◽

...

Keyword(s):

Functional Properties ◽

Sickle Cell ◽

Globin Gene ◽

Crystal Formation ◽

Local Health ◽

Hb S ◽

In Trans ◽

Α Chain ◽

Chain Variant ◽

Hb C

Abstract The occurrence of multiple globin abnormalities in one individual is not very rare, particularly in populations where hemoglobinopathies are common. In most cases, this is of genetic interest and may pose a diagnostic challenge due to the interaction of the products of mutant α and β globin genes and the presence of hybrid hemoglobins. Co-inheritance of α globin variants with sickle cell disease (Hb SS or SC) could have an effect on the disease phenotype particularly when the variant in question has altered functional properties (decreased or increased oxygen affinity) or stability. We report a patient with Hb SC disease with co-inheritance of the α chain variant, Hb Chicago (α136Leu→Met), and deletional α thalassemia (−α3.7) in trans to the Hb Chicago mutation. The patient is a 3-year old African-American male referred to the Pediatric Sickle Cell Clinic from the local Health Department. He is the product of an uneventful term pregnancy and a normal labor. He presented with seizures at age 3 weeks and underwent a neurologic evaluation which failed to reveal any abnormality. His subsequent course was uneventful without further seizures after 1 year of age and no hospitalizations. Physical exam was unremarkable with normal growth. A CBC showed Hb of 11.3 g/dl, Hct 35.2%, MCV 64.8 fl, MCH 20.8, MCHC 32.1, RDW 18.4%, retic count of 1.7% (absolute retic count of 92,480). Cation exchange HPLC revealed a Hb F of 6.8%, A2 3.3%, Hb S 33.1% and Hb C 30.0%. Both Hb S and Hb C peaks were followed by an additional peak of 13.2% (Hb SX) and 13.6% (Hb CX) respectively suggesting the presence of an α chain variant. The total quantity of Hb S was 46.3% (Hb S+Hb SX) and that of Hb C was 43.6% (Hb C+ Hb CX), whereas Hb X amounted to 26.8%. A reversed phase HPLC confirmed the presence of an α chain variant, which eluted earlier than normal α chains; αX constituted 37.5% of the total α chains. Sequencing of the β-globin gene confirmed the presence of Hb S (GAG→GTG) and Hb C (GAG→AAG) mutations in codon 6. A PCR for α globin deletions confirmed heterozygosity for the -α3.7 deletion. α globin sequencing revealed an apparent homozygosity for a CTG→ATG (Leu→Met) substitution of the codon 136 in α2 globin gene; this “apparent” homozygosity is due to the -α3.7 deletion in trans. Family studies showed that the patient’s mother had Hb C trait with heterozygous α-thalassemia; the father was not available. The paternal grandmother had normal α-globin gene numbers, with heterozygous Hb Chicago, which was quantitated at 20.7%. Thus, the patient’s genotype was ascertained as βS/βC;-α/αChicagoα. Hb Chicago has been reported in conjunction with Hb SS but not with Hb SC disease. The co-inheritance of the α-chain variant, Hb G-Philadelphia (α68Asn→Lys) and Hb SC disease, has been reported by Lawrence et al (Blood90:2819–25, 1997); this combination resulted in the acceleration of Hb C crystal formation and decreased Hb S polymerization with a resultant mild sickling disorder. α136 is a heme contact; the Leu→Met substitution in Hb Chicago does not alter the functional properties or the stability of the molecule and is not associated with any hematologic abnormalities in heterozygous carriers. This residue is not involved in intermolecular contacts of deoxy Hb S and hence is not expected to alter the kinetics of deoxy Hb S polymerization. The significance of this observation is the accurate diagnosis of the complex Hb phenotype and ascertainment of its lack of interaction with the sickling or crystallization process.

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Hemoglobins in Togolese Newborns: Hb S, Hb C, Hb Bart's, and α-Globin Gene Status

American Journal of Hematology ◽

10.1002/(sici)1096-8652(199811)59:3<208::aid-ajh5>3.0.co;2-r ◽

1998 ◽

Vol 59 (3) ◽

pp. 208-213 ◽

Cited By ~ 15

Author(s):

Akueté Yvon Segbena ◽

Claude Prehu ◽

Henri Wajcman ◽

Josiane Bardakdjian-Michau ◽

Kodjovi Messie ◽

...

Keyword(s):

Globin Gene ◽

Hb S ◽

Gene Status ◽

Hb Bart's ◽

Hb C

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Hemoglobin C/Korle-Bu Identified In A Patient With A Previous Diagnosis Of Hemoglobin S/C Disease

American Journal of Clinical Pathology ◽

10.1093/ajcp/aqaa161.242 ◽

2020 ◽

Vol 154 (Supplement_1) ◽

pp. S110-S111

Author(s):

D Dolezal ◽

C Tormey ◽

H Rinder ◽

A J Siddon

Keyword(s):

Cellulose Acetate ◽

Hospital Admissions ◽

Globin Gene ◽

Clinical Manifestations ◽

Gene Sequencing ◽

American Woman ◽

Target Cells ◽

Hemoglobin C ◽

Hb S ◽

Hb C

Abstract Casestudy Hemoglobin Korle-Bu (Hb-KB) is an uncommon Hb variant that can be mistaken for Hb-S on electrophoretic screening. While Hb-KB alone has no clinical manifestations, there are only limited case studies describing KB in combination with other Hb variants. Here we report a rare case of Hb-C/KB misdiagnosed and managed as Hb-S/C disease for over 20 years. Results A 21-year-old African American woman with presumed Hb-S/C disease presented with generalized abdominal pain, nausea, and vomiting. In 1999, Hb electrophoresis showed 59% of abnormal hemoglobin presumed to be HbS and 41% HbC+A2; agar/acetate gel analysis was not employed and the hemoglobinopathy remained incompletely characterized. She had a history of back, chest, abdomen, and extremity pains requiring multiple hospital admissions, with treatments including dilaudid, oxycontin, oxycodone, and hydroxyurea. Her vital signs were normal and her examination was only significant for abdominal tenderness. Imaging studies did not show any evidence vascular occlusion, avascular necrosis, or end-organ dysfunction. RBC indices were remarkable for mild borderline anemia, microcytosis, decreased MCH/elevated MCHC, and borderline elevated RDW. Peripheral smear showed microcytic red cells with anisocytosis, scattered target cells, and a notable absence of sickled cells and Hb-C-crystals. The diagnosis of Hb-S/C disease was then revisited. HPLC showed abnormal hemoglobins in the Hb-D window at 55.1% and in the Hb-C window at 40.6%, with 3.5% Hb-A2 and no normal Hb-A. Gel electrophoresis with cellulose acetate followed by citrate agar suggested Hb-C in combination with either D, G, or Korle-Bu. Definitive diagnosis was obtained by beta globin gene sequencing that demonstrated one copy Hb-C (19G>A, Glu7Lys) and one copy Hb- Korle-Bu (220G>A, Asp74Asn). Given the absence of Hb-S/C disease, her gastrointestinal distress and pain episodes were re-evaluated. Conclusion Hb-S and Hb-Korle-Bu migrate similarly in cellulose acetate electrophoresis but can be distinguished on citrate agar. Challenging beta chain variants can now be readily differentiated by complete gene sequencing. This case study emphasizes the importance of distinguishing Hb-KB from clinically-significant Hb-S.

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HB Yuoa orαl30(H13)ALA→ASP;: A New α Chain Variant with Low Oxygen Affinity

Hemoglobin ◽

10.3109/03630269209005698 ◽

1992 ◽

Vol 16 (5) ◽

pp. 435-439 ◽

Cited By ~ 8

Author(s):

K. Fujisawa ◽

Y. Hattori ◽

Y. Ohba ◽

S. Ando

Keyword(s):

Oxygen Affinity ◽

Low Oxygen ◽

Α Chain ◽

Chain Variant ◽

Low Oxygen Affinity

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Evaluation of the CapillaryS 2 CE System for Hemoglobinopathy Investigations.

Blood ◽

10.1182/blood.v108.11.3781.3781 ◽

2006 ◽

Vol 108 (11) ◽

pp. 3781-3781

Author(s):

Andrew G. McFarlane ◽

Linda M. Halchuk ◽

Barry Eng ◽

John Waye ◽

Mark A. Crowther

Keyword(s):

Newborn Screening ◽

High Performance ◽

Rare Variants ◽

Nucleotide Sequencing ◽

Hemoglobin E ◽

Hb E ◽

Hb S ◽

Hb H Disease ◽

User Friendly ◽

Hb C

Abstract Traditional diagnosis of hemoglobinopathies rely on separation and accurate quantification of hemoglobin (Hb) fractions using alkaline and acid electrophoresis, isoelectric focusing (IEF) and/or High Performance Liquid Chromatography (HPLC). Recent reports have suggested capillary electrophoresis (CE) as an alternate method for screening. We evaluated a new CE system the Sebia CapillaryS 2 (Evry Cedex, France) and compared it to IEF and HPLC. For this evaluation samples referred to our laboratory for routine hemoglobinopathy screening or as cord bloods sent for confirmation of a variant detected as a result of newborn screening were analyzed using all three techniques. IEF was performed with the Resolve IEF kit (Perkin Elmer,Wallac Oy, Finland). HPLC was done on the BioRad Variant II (Munich, Germany) using the Hb A2/Hb A1c Dual program. The CE was performed using the “Capillarys Hemoglobin(E) kit”. Suspected rare variants were further investigated with DNA investigations, including PCR and direct nucleotide sequencing. Variant hemoglobins were detected in 156 of 764 samples (Table 1). The correlation between IEF, HPLC and CE was excellent. One variant (Hb Toulon) was not detected by the CE but ran with Hb F. The CE system did not report the Hb F value on samples with very low (< 1.0%) Hb F by HPLC. Two cases of Hb Constant Spring were identified by CE but not by either IEF or HPLC. The correlation of both Hb F and Hb A2 reported between the CE and HPLC systems were excellent (R > 0.99 and 0.98, Figure 1 and Figure 2 respectively). The positive bias of Hb A2 seen in HPLC when Hb S is present was lower in the CE. However, the CE system demonstrated a negative bias for Hb A2 if Hb C was present. CE was the only system capable of separating Hb A2 from Hb E. We conclude that CE is comparable to both IEF and HPLC for separation and quantification of hemoglobin fractions; this system has the added advantage of reporting Hb A2 in the presence of Hb E and consistently identifies Hb Constant Spring, which is not easily detected on IEF or HPLC. Further this CE system is user friendly and holds promise as a tool for newborn screening and routine laboratory hemoglobinopathy investigations. Hemoglobinopathy Detected Hemoglobinopathy Number β Thalassemia 99 Hb S trait 55 Cord with Hb Barts 28 Hb C trait 13 Hb E trait 12 Hb D trait 8 α variant (not yet identified) 5 Hb Barts + Hb S trait 4 Hb Barts + Hb D trait 3 Hb S disease 3 Hb Barts + Hb E trait 2 Hb E +β Thalassemia 2 Hb H disease 2 Hb Constant Spring 2 Hb J Baltimore 2 Hb Toulon 2 δ variant (not identified) 2 Hb S + Hb C 1 Hb Barts + Hb C trait 1 Hb Q Thailand + --SEA/αα 1 Homozygous Hb E + Hb Constant Spring 1 Hb S + Hb Kenya 1 Hb J Roviga 1 Hb Beograd 1 Hb G Coushatta 1 Hb Sirian 1 Hb Titusville 1 B variant (not identified yet) 1 Total Abnormal 255 No hemoglobinopathy detected 509 Total 764 Hb F: HPLC vs CE Hb F: HPLC vs CE Hb A2: HPLC vs CE Hb A2: HPLC vs CE

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Low Oxygen Affinity Variant Haemoglobin in an elderly woman presenting with low oxygen saturation

Acute Medicine Journal ◽

10.52964/amja.0431 ◽

2015 ◽

Vol 14 (2) ◽

pp. 72-76

Author(s):

Norris E. Igbineweka ◽

◽

Gillian A. Horne ◽

Mark Basil Jackson ◽

Timothy J. Chevassut ◽

...

Keyword(s):

Oxygen Saturation ◽

Globin Gene ◽

Oxygen Affinity ◽

Blood Gas Analysis ◽

Gas Analysis ◽

Low Oxygen ◽

Arterial Blood Gas ◽

Arterial Blood ◽

Pulmonary Angiogram ◽

Normal Chest

An asymptomatic 81-year-old woman was referred by her general practitioner regarding a pulse-oximetry oxygen saturation (SpO2) of 74%. An arterial blood gas analysis (ABG) on air showed PaO2 12.9 kPa, oxygen saturation 80%, with normal pH, PaCO2, methaemoglobin and carboxyhaemoglobin levels. After a normal chest x-ray, tinzaparin was administered empirically for possible occult pulmonary embolus. This diagnosis was subsequently excluded with an unremarkable computed tomography pulmonary angiogram (CTPA). She was further investigated as an out patient. DNA globin-gene analysis identified a variant haemoglobin revealed to be haemoglobin Saint Mande (HbSM). Following reassurance regarding the benign nature of her condition, she has remained well.

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