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Oliveira JL, Thompson CH, Saravanaperumal SA, Koganti T, Jenkinson G, Hein MS, Kohorst MA, Hasadsri L, Nguyen PL, Matern D, Kipp BR, Klee EW, Wieben ED, Hoyer JD, Rangan A. εγ-Thalassemia, a New Hemoglobinopathy Category. Clin Chem 2023:7136664. [PMID: 37086467 DOI: 10.1093/clinchem/hvad038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Accepted: 03/07/2023] [Indexed: 04/24/2023]
Abstract
BACKGROUND Large β-globin gene cluster deletions (hereditary persistence of fetal hemoglobin [Hb] or β-, δβ-, γδβ-, and ϵγδβ-thalassemia), are associated with widely disparate phenotypes, including variable degrees of microcytic anemia and Hb F levels. When present, increased Hb A2 is used as a surrogate marker for β-thalassemia. Notably, ϵγδβ-thalassemias lack the essential regulatory locus control region (LCR) and cause severe transient perinatal anemia but normal newborn screen (NBS) results and Hb A2 levels. Herein, we report a novel deletion of the ϵ, Aγ, Gγ, and ψβ loci with intact LCR, δ-, and β-regions in 2 women and newborn twins. METHODS Capillary electrophoresis (CE), high-performance liquid chromatography (HPLC), DNA sequencing, multiplex ligation-dependent probe amplification (MLPA), gap-polymerase chain reaction (gap-PCR), and long-read sequencing (LRS) were performed. RESULTS NBS showed an Hb A > Hb F pattern for both twins. At 20 months, Hb A2 was increased similarly to that in the mother and an unrelated woman. Unexplained microcytosis was absent and the twins lacked severe neonatal anemia. MLPA, LRS, and gap-PCR confirmed a 32 599 base pair deletion of ϵ (HBE1) through ψβ (HBBP1) loci. CONCLUSIONS This deletion represents a hemoglobinopathy category with a distinct phenotype that has not been previously described, an ϵγ-thalassemia. Both the NBS Hb A > F pattern and the subsequent increased Hb A2 without microcytosis are unusual. A similar deletion should be considered when this pattern is encountered and appropriate test methods selected for detection. Knowledge of the clinical impact of this new category will improve genetic counselling, with distinction from the severe transient anemia associated with ϵγδβ-thalassemia.
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Affiliation(s)
- Jennifer L Oliveira
- Division of Hematopathology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, United States
| | | | | | - Tejaswi Koganti
- Department of Clinical Genomics, Quantitative Health Sciences - Computational Biology, Mayo Clinic, Rochester, MN, United States
| | - Garrett Jenkinson
- Department of Clinical Genomics, Quantitative Health Sciences - Computational Biology, Mayo Clinic, Rochester, MN, United States
| | - Molly S Hein
- Division of Hematopathology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, United States
| | - Mira A Kohorst
- Department of Pediatric Hematology-Oncology, Mayo Clinic, Rochester, MN, United States
| | - Linda Hasadsri
- Division of Laboratory Genetics and Genomics, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, United States
| | - Phuong L Nguyen
- Division of Hematopathology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, United States
| | - Dietrich Matern
- Division of Laboratory Genetics and Genomics, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, United States
| | - Benjamin R Kipp
- Division of Laboratory Genetics and Genomics, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, United States
| | - Eric W Klee
- Department of Clinical Genomics, Quantitative Health Sciences - Computational Biology, Mayo Clinic, Rochester, MN, United States
| | - Eric D Wieben
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN, United States
- Department of Clinical Genomics, Quantitative Health Sciences - Computational Biology, Mayo Clinic, Rochester, MN, United States
| | - James D Hoyer
- Division of Hematopathology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, United States
| | - Aruna Rangan
- Division of Hematopathology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, United States
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Rangan A, Hein MS, Jenkinson WG, Koganti T, Aleff RA, Hilker CA, Blommel JH, Porter TR, Swanson KC, Lundquist P, Nguyen PL, Shi M, He R, Viswanatha DS, Jen J, Klee EW, Kipp BR, Hoyer JD, Wieben ED, Oliveira JL. Improved Characterization of Complex β-Globin Gene Cluster Structural Variants Using Long-Read Sequencing. J Mol Diagn 2021; 23:1732-1740. [PMID: 34839893 DOI: 10.1016/j.jmoldx.2021.08.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2021] [Revised: 07/30/2021] [Accepted: 08/18/2021] [Indexed: 10/19/2022] Open
Abstract
Complex insertion-deletion (indel) events in the globin genes manifest in widely variable clinical phenotypes. Many are incompletely characterized because of a historic lack of efficient methods. A more complete assessment enables improved prediction of clinical impact, which guides emerging therapeutic choices. Current methods have limited capacity for breakpoint assignment and accurate assessment of mutation extent, especially in cases containing duplications or multiple deletions and insertions. Technology, such as long-read sequencing, holds promise for significant impact in the characterization of indel events because of read lengths that span large regions, resulting in improved resolution. Four known complex β-globin gene cluster indel types were assessed using single-molecule, real-time sequencing technology and showed high correlation with previous reports, including the Caribbean locus control deletion (g.5,305,478_5,310,336del), a large β-gene duplication containing the Hb S mutation (g.4,640,335_5,290,171dup with g.5,248,232T>A, c.20A>T; variant allele fraction, 64%), and two nested variants (double deletions with intervening inversion): the Indian Gγ(Aγδβ)0-thalassemia (g.5,246,804-5,254,275del, g.5,254,276_5,269,600inv, and g.5,269,601_5,270,442del) and the Turkish/Macedonian (δβ)0 thalassemia (g.5,235,064_5,236,652del, g.5,236,653_5,244,280inv, and g.5,244,281_5,255,766del). Our data confirm long-read sequencing as an efficient and accurate method to identify these clinically significant complex events. Limitations include high-complexity sample preparation requirements, which hinder routine use in clinical laboratories. Continued improvements in sample and data workflow processes are needed to accommodate volumes in a tertiary clinical laboratory.
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Affiliation(s)
- Aruna Rangan
- Division of Hematopathology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota.
| | - Molly S Hein
- Division of Hematopathology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | | | - Tejaswi Koganti
- Biomedical Statistics and Informatics, Mayo Clinic, Rochester, Minnesota
| | - Ross A Aleff
- Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota
| | | | - Joseph H Blommel
- Advanced Diagnostics Laboratory, Mayo Clinic, Rochester, Minnesota
| | - Tavanna R Porter
- Division of Hematopathology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - Kenneth C Swanson
- Division of Hematopathology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - Patrick Lundquist
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - Phuong L Nguyen
- Division of Hematopathology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - Min Shi
- Division of Hematopathology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - Rong He
- Division of Hematopathology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - David S Viswanatha
- Division of Hematopathology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - Jin Jen
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - Eric W Klee
- Biomedical Statistics and Informatics, Mayo Clinic, Rochester, Minnesota
| | - Benjamin R Kipp
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - James D Hoyer
- Division of Hematopathology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - Eric D Wieben
- Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota
| | - Jennifer L Oliveira
- Division of Hematopathology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota.
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Rangan A, Savedra ME, Dergam-Larson C, Swanson KC, Szuberski J, Go RS, Porter TR, Brunker SE, Shi M, Nguyen PL, Hoyer JD, Oliveira JL. Interpreting sulfhemoglobin and methemoglobin in patients with cyanosis: An overview of patients with M-hemoglobin variants. Int J Lab Hematol 2021; 43:837-844. [PMID: 34092029 DOI: 10.1111/ijlh.13581] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 04/28/2021] [Accepted: 04/28/2021] [Indexed: 01/17/2023]
Abstract
INTRODUCTION Methemoglobin (MetHb) and sulfhemoglobin (SHb) measurements are useful in the evaluation of cyanosis. When one or both values are elevated, additional analysis is important to establish the etiology of the disorder. Methemoglobinemia occurs from acquired or hereditary causes with diverse treatment considerations, while true sulfhemoglobinemia is only acquired and treatment is restricted to toxin removal. Some toxic exposures can result in a dual increase in MetHb and SHb. Hereditary conditions, such as M-Hemoglobin variants (M-Hbs), can result in increased MetHb and/or SHb values but are clinically compensated and do not require treatment if they are cyanotic but otherwise clinically well. METHODS Herein, we report 53 hemoglobin variant cases that have associated MetHb and SHb levels measured by an adapted Evelyn-Malloy laboratory assay method. RESULTS Our data indicate M-Hbs cause variable patterns of MetHb and SHb elevation in a fairly reproducible pattern for the particular variant. In particular, α globin chain M-Hbs can mimic acquired sulfhemoglobinemia due to an isolated increased SHb value. CONCLUSION If the patient appears clinically well other than cyanosis, M-Hbs should be considered early in the evaluation process to differentiate from acquired conditions to avoid unnecessary testing and treatment regimens and prompt genetic counseling.
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Affiliation(s)
- Aruna Rangan
- Division of Hematopathology, Mayo Clinic, Rochester, MN, USA
| | | | | | | | | | - Ronald S Go
- Department of Hematology and Oncology, Mayo Clinic, Rochester, MN, USA
| | | | - Sarah E Brunker
- Division of Hematopathology, Mayo Clinic, Rochester, MN, USA
| | - Min Shi
- Division of Hematopathology, Mayo Clinic, Rochester, MN, USA
| | - Phuong L Nguyen
- Division of Hematopathology, Mayo Clinic, Rochester, MN, USA
| | - James D Hoyer
- Division of Hematopathology, Mayo Clinic, Rochester, MN, USA
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